pku1833 排列(use next_permutation)

next_permutation函数是stl里的库函数，用来求排列。

Parameters

first, last

Bidirectional iterators to the initial and final positions of the sequence. The range used is [first,last), which contains all the elements between first and last, including the element pointed by first but not the element pointed by last.

comp

Comparison function object that, taking two values of the same type than those contained in the range, returns true if the first argument is to be considered less than the second argument.

Return value

不用comp参数就是返回增排列

1. /*pku 1833
2.   Name: 排列
3.   Date: 28-07-08 10:56
4.   Description: use next_permutaion
5. */
6. // next_permutation
7. #include <iostream>
8. #include <algorithm>
9. using namespace std;
10. #include<stdio.h>
11. #define pr printf
12. int n;
13. int main(){
14.     int k,a[1025],t,tmp,i;
15.     scanf("%d",&t);
16.     while(t--){
17.         scanf("%d%d",&n,&k);
18.         if(n<=4){
19.             for(tmp=1,i=1;i<=n;i++)tmp*=i;   
20.             k%=tmp;
21.         }
22.         for(int i=0;i<n;i++){
23.             scanf("%d",&a[i]);
24.         }
25.         while(k!=0){
26.             if(!next_permutation(a,a+n))
27.                 {
28.                     for(i=0;i<n;i++)a[i]=i+1;   
29.                 }
30.             k--;
31.         }
32.         for(i=0;i<n;i++)
33.             pr("%d ",a[i]);
34.                 pr("/n");
35.         }   
36. }