Function calc

LeetCode_problems/Permutation Sequence/Solution.cpp:7–20

string s="";
int c=0;
void calc(int  n,int k,int m,vector<int > &v){ //m always decreases by 1 
    if(m<0){
    	return ;
    }
    
    int d=fact[m];// factorial of m 
    
    int x=ceil(k*1.0/d*1.0);// index of the element that has to be taken from vector
    c=c*10 + v[x-1];        // forming the number 
    s=to_string(c);         // converting  number to string 
    v.erase(v.begin()+x-1);  // now remove that digit as permutation has every digit once
    int next_k=k-((x-1)*d);     // finding the next k which is to be further processed with the same logic
    calc(n,next_k,m-1,v);   //its a recursive function
}


class Solution {