string, SA, djs

Author: tjd229

algospot/HABIT.cpp

@@ -0,0 +1,98 @@
+//category : string, SA, djs
+
+#include <iostream>
+#include <string>
+#include <vector>
+#include <algorithm>
+#define pii pair<int,int>
+using namespace std;
+int g[4001];
+int lcp[4001];
+int tmp[4001];
+int s_ix[4001];
+int p[4001];
+int sz[4001];
+bool cover[4001];
+int d;
+bool cmp(int a, int b){
+	if (g[a] != g[b]) return g[a] < g[b];
+	return g[a + d] < g[b + d];
+}
+int find(int a){
+	if (a != p[a]) p[a] = find(p[a]);
+	return p[a];
+}
+void join(int a, int b){
+	a = find(a);
+	b = find(b);
+	if (a == b) return;
+	p[b] = a;
+	sz[a] += sz[b];
+}
+int main(){
+	int i, j;
+	int C;
+	int K;
+	int ans;
+	string s;
+	cin >> C;
+	while (C--){
+		cin >> K >> s;
+		if (K == 1){
+			cout << s.size() << "\n";
+			continue;
+		}
+		for (i = 0; i < s.size(); i++){
+			s_ix[i] = i;
+			g[i] = s[i];
+			cover[i] = false;
+			p[i] = i;
+			sz[i] = 0;
+		}
+		ans = 0;
+		g[i] = -1;
+		cover[i] = false;
+		d = 1;
+		do{
+			sort(s_ix, s_ix + s.size(), cmp);
+			tmp[s_ix[0]] = 0;
+			for (i = 1; i < s.size(); i++)
+				tmp[s_ix[i]] = tmp[s_ix[i - 1]] + cmp(s_ix[i - 1], s_ix[i]);
+			for (i = 0; i < s.size(); i++)
+				g[i] = tmp[i];
+			d <<= 1;
+		} while (s.size() - 1 != g[s_ix[s.size() - 1]]);
+		d = 0;
+		vector<pii > v;
+		for (i = 0; i < s.size(); i++){
+			if (g[i] == 0) continue;
+			j = s_ix[g[i] - 1];
+			d = max(d - 1, 0);
+			lcp[g[i]] = 0;
+			while (i + d < s.size() && j + d < s.size() && s[j + d] == s[i + d])
+				lcp[g[i]] = ++d;
+			d = lcp[g[i]] - 1;
+			//cout << lcp[g[i]] << "," << i << endl;
+			if (lcp[g[i]] > 0){
+				sz[g[i]] = 1;
+				v.push_back({lcp[g[i]],g[i]});
+			}
+		}
+		sort(v.begin(), v.end());
+		while (!v.empty()){
+			i = v.back().second;
+			if (cover[i - 1]) join(i - 1, i);
+			if (cover[i + 1]) join(i, i+1);
+			//cout << sz[find(i)] << ","<<v.back().first << endl;
+			if (sz[find(i)] + 1 >= K){
+				ans = v.back().first;
+				break;
+			}
+			cover[i] = true;
+			v.pop_back();
+		}
+		cout << ans << "\n";
+	}
+
+	return 0;
+}