24

#024:Lexicographic_permutations.cpp

@@ -0,0 +1,38 @@
+#include <cmath>
+#include <cstdio>
+#include <vector>
+#include <iostream>
+#include <algorithm>
+using namespace std;
+
+typedef unsigned long long ull ;
+// # define fract13 6227020800
+# define X 479001600 // 13! / 13
+
+int main() {
+    ull         n, x, k;
+    short       q, size;
+    vector<char> v = {'a', 'b', 'c', 'd', 'e', 'f', 'j', 'h', 'j', 'k', 'l', 'm'}, tmp;
+
+    cin >> q;
+    for (short i = 0; i < q; i++)
+    {
+        cin >> n;
+        n--;
+        tmp = v;
+        x = X;
+        size = 13;
+        while (size) 
+        {
+            k = (n / x);
+            cout << tmp[k];
+            tmp.erase(tmp.begin() + k);
+            n -= (n / x) * x;
+            --size;
+            x /= size;
+        }
+        cout << endl;
+        tmp.clear();
+    }
+    return 0;
+}

README.md

@@ -98,4 +98,7 @@ ___
 
 [Hackerrank] Given N, print YES if it can be expressed as sum of two abundant numbers, else print NO.
 
-[projecteuler] Find the sum of all positive integers that cannot be written as the sum of two abundant numbers.
+[projecteuler] Find the sum of all positive integers that cannot be written as the sum of two abundant numbers.
+___
+## <a href=https://www.hackerrank.com/contests/projecteuler/challenges/euler024/problem?isFullScreen> Problem 24: </a>  Lexicographic permutations <sup>[Easy]</sup>
+What is the N<sup>th</sup> lexicographic permutation of the word "abcdefghijklm".