Vijos 1092 全排列

题目链接

来个水题。。难得的1Y。

 #include <cstdio>
 #include <cstring>
 #include <iostream>
 using namespace std;
 #define LL __int64
 int flag[],que[];
 LL fact[];
 int n;
 LL m;
 void dfs(LL x,int step)
 {
     LL temp = ;
     int i;
     for(i = ;i <= n;i ++)
     {
         if(!flag[i])
         {
             if(temp + fact[n-step] >= x)
             {
                 flag[i] = ;
                 que[step] = i;
                 dfs(x-temp,step+);
                 return ;
             }
             temp += fact[n-step];
         }
     }
 }
 int main()
 {
     int i;
     fact[] = ;
     for(i = ;i <= ;i ++)
     fact[i] = fact[i-]*i;
     scanf("%d%I64d",&n,&m);
     dfs(m,);
     for(i = ;i <= n;i ++)
     {
         if(i == )
         printf("%d",que[i]);
         else
         printf(" %d",que[i]);
     }
     printf("\n");
     return ;
 }