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arknavearknave
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Codeforces rounds
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10 files changed

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‎codeforces/237/c.cpp‎

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#include <cstdio>
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#include <cstring>
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using namespace std;
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const int MAXN = 1000006;
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// sieve[i] = 0 iff i is prime
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bool sieve[MAXN];
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int cum[MAXN];
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int a, b, k;
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void gen_sieve() {
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memset(sieve, 0, sizeof(sieve));
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sieve[0] = sieve[1] = 1;
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for (int i = 4; i < MAXN; i += 2) {
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sieve[i] = 1;
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}
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for (int i = 3; i < MAXN; i += 2) {
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if (!sieve[i]) {
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for (long long j = 1LL * i * i; j < MAXN; j += i) {
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sieve[j] = 1;
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}
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}
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}
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}
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void gen_cum() {
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cum[0] = 0;
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for (int i = 1; i < MAXN; ++i) {
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cum[i] = cum[i - 1] + (sieve[i] == 0);
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}
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}
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bool works(int l) {
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for (int x = a; x + l - 1 <= b; ++x) {
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// printf("Interval [%d, %d] has %d primes\n", x, x + l - 1, cum[x + l - 1] - cum[x - 1]);
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if (cum[x + l - 1] - cum[x - 1] < k)
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return false;
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}
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return true;
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}
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int main() {
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scanf("%d %d %d", &a, &b, &k);
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gen_sieve();
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gen_cum();
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if (!works(b - a + 1)) {
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printf("%d\n", -1);
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} else if (works(1)) {
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printf("%d\n", 1);
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} else {
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int lo = 1;
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int hi = b - a + 1;
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while (lo + 1 < hi) {
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int mid = (lo + hi) / 2;
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if (works(mid)) {
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hi = mid;
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} else {
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lo = mid;
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}
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}
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printf("%d\n", hi);
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}
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return 0;
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}

‎codeforces/475/b.py‎

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def main():
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n, m = map(int, input().split())
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a = input()
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b = input()
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valid = (a[0] == '>' and a[-1] == '<' and b[0] == '^' and b[-1] == 'v') \
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or (a[0] == '<' and a[-1] == '>' and b[0] == 'v' and b[-1] == '^')
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print("YES" if valid else "NO")
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main()

‎codeforces/609/e.cpp‎

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#include <cstdio>
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#include <cstring>
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#include <cmath>
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#include <algorithm>
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#include <utility>
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#include <vector>
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#include <queue>
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using namespace std;
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const int MAXN = 200005;
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const int LOGN = 19;
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int n, m;
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struct edge {
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int u, v, w;
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bool operator<(const edge& other) const {
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return w < other.w;
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}
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};
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vector<edge> edges;
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int uf[MAXN];
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void init() {
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for (int i = 1; i <= n; ++i)
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uf[i] = i;
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}
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int find(int x) {
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int p = uf[x];
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if (uf[p] != p)
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p = find(p);
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return uf[x] = p;
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}
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void join(int x, int y) {
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int xr = find(x);
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int yr = find(y);
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if (xr == yr) return;
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uf[xr] = yr;
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}
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vector<pair<int, int> > tree[MAXN];
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int parent[MAXN][LOGN];
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int big[MAXN][LOGN];
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int depth[MAXN];
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long long find_mst() {
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vector<edge> sorted(edges.begin(), edges.end());
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sort(sorted.begin(), sorted.end());
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init();
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long long mst_cost = 0LL;
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for (const edge& edg : sorted) {
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if (find(edg.u) != find(edg.v)) {
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tree[edg.u].push_back({edg.v, edg.w});
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tree[edg.v].push_back({edg.u, edg.w});
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join(edg.u, edg.v);
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mst_cost += edg.w;
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}
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}
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return mst_cost;
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}
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void dfs(int node, int par, int dep) {
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parent[node][0] = par;
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depth[node] = dep;
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for (pair<int, int> child : tree[node]) {
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if (child.first != par) {
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dfs(child.first, node, dep + 1);
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big[child.first][0] = child.second;
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}
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}
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}
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void gen_parents() {
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for (int j = 1; j < LOGN; ++j) {
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for (int i = 1; i <= n; ++i) {
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if (parent[i][j - 1] != -1) {
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parent[i][j] = parent[parent[i][j - 1]][j - 1];
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big[i][j] = max(big[i][j - 1], big[parent[i][j - 1]][j - 1]);
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}
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}
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}
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}
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int walk_up(int node, int move) {
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int par = node;
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for (int j = 0, p = 1; par != -1 and p <= move; ++j, p <<= 1) {
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if (move & p) {
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par = parent[par][j];
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}
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}
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return par;
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}
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int find_max(int node, int move) {
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int loc = node;
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int val = 0;
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for (int j = 0, p = 1; loc != -1 and p <= move; ++j, p <<= 1) {
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if (move & p) {
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val = max(val, big[loc][j]);
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loc = parent[loc][j];
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}
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}
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return val;
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}
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int lca(int x, int y) {
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if (depth[x] > depth[y])
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return lca(y, x);
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if (depth[x] < depth[y])
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y = walk_up(y, depth[y] - depth[x]);
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if (x == y) return x;
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int lo = 0;
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int hi = n;
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while (lo + 1 < hi) {
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int mid = (lo + hi) / 2;
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if (walk_up(x, mid) == walk_up(y, mid))
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hi = mid;
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else
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lo = mid;
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}
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return walk_up(x, hi);
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}
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int main() {
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scanf("%d %d", &n, &m);
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int u, v, w;
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for (int i = 0; i < m; ++i) {
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scanf("%d %d %d", &u, &v, &w);
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edges.push_back({u, v, w});
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}
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long long cost = find_mst();
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memset(parent, -1, sizeof(parent));
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dfs(1, -1, 0);
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gen_parents();
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for (int i = 0; i < m; ++i) {
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u = edges[i].u;
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v = edges[i].v;
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int l = lca(u, v);
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// printf("%d %d %d\n", u, v, l);
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if ((l == u or l == v) and (depth[u] - depth[v] == 1 or depth[v] - depth[u] == 1)) {
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printf("%lld\n", cost);
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} else {
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long long m1 = find_max(u, depth[u] - depth[l]);
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long long m2 = find_max(v, depth[v] - depth[l]);
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printf("%lld\n", cost - max(m1, m2) + edges[i].w);
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}
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}
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return 0;
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}

‎codeforces/660/a.cpp‎

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#include <cstdio>
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#include <vector>
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using namespace std;
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inline int gcd(int a, int b) {
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return b == 0 ? a : gcd(b, a % b);
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}
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int main() {
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int n;
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scanf("%d", &n);
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vector<int> vals;
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int x;
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scanf("%d", &x);
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vals.push_back(x);
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int extra = 0;
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for (int i = 1; i < n; ++i) {
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scanf("%d", &x);
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if (gcd(vals.back(), x) > 1) {
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++extra;
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vals.push_back(1);
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}
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vals.push_back(x);
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}
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printf("%d\n", extra);
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for (int x : vals)
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printf("%d ", x);
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printf("\n");
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return 0;
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}

‎codeforces/675/d.cpp‎

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#include <cstdio>
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#include <cassert>
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#include <set>
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using namespace std;
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set<int> full_left;
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set<int> full_right;
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set<int> values;
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set<int> neg_values;
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int main() {
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int n;
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scanf("%d", &n);
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int x;
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scanf("%d", &x);
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values.insert(x);
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neg_values.insert(-x);
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for (int i = 1; i < n; ++i) {
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scanf("%d", &x);
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// handle the edge cases
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if (x < *values.begin()) {
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full_left.insert(*values.begin());
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printf("%d ", *values.begin());
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} else if (x > *values.rbegin()) {
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full_right.insert(*values.rbegin());
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printf("%d ", *values.rbegin());
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} else {
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// find the nodes surrounding x
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int lower = -1 * (*neg_values.upper_bound(-x));
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int upper = *values.upper_bound(x);
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// printf("%d %d %d\n", lower, x, upper);
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assert(full_right.count(lower) ^ full_left.count(upper));
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if (full_right.find(lower) == full_right.end()) {
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full_right.insert(lower);
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printf("%d ", lower);
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} else {
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full_left.insert(upper);
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printf("%d ", upper);
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}
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}
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values.insert(x);
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neg_values.insert(-x);
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}
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}

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