HACKER RANK Project Euler 24 - Lexicographic Permutations - Solution.'C++'

Project Euler Challenges-24 - Lexicographic Permutations Solution

Problem Statement

This problem is a programming version of Problem 24 from projecteuler.net

A permutation is an ordered arrangement of objects. For example, dabc is one possible permutation of the word abcd. If all of the permutations are listed alphabetically, we call it lexicographic order. The lexicographic permutations of abc are: 

abc   acb   bac   bca   cab   cba

What is the Nth lexicographic permutation of the word abcdefghijklm?

Input Format 
The first line contains an integer T , i.e., number of test cases. 
Next T lines will contain an integer N.

Output Format 
Print the values corresponding to each test case.

Constraints 
1≤T≤1000 
1≤N≤13!

Sample Input

2
1
2

Sample Output

abcdefghijklm
abcdefghijkml

Solution:

#include <string>
#include <algorithm>
#include <cstdio>
using namespace std;

int main(){
 
 string v="abcdefghijklm";
 int T;
 long long _o=1;for(int i=1;i<=v.size();i++)_o*=i;
 long long i=1000000,j;
 for(scanf("%d",&T);T--;){
 scanf("%lld",&i);
 i-=1;
 long long o=_o;
 string V=v,a;
 for(;V.size();){
  //j=i%o/(o=o/V.size()); ///(o=o+3>>2);
  j=i%o,o/=V.size(),j/=o;
  a+=V[j];
  V.erase(V.begin()+j);
 }
 puts(a.c_str());
 }
}

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