next_permutation（全排列函数）

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next_permutation用于求当前排列的下一个排列情况

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

int main()
{
	int a[5]={1,2,3,4};
	
	for (int i=1; i<=24; i++){
		printf("%d%d%d%d\n", a[0],a[1],a[2],a[3]);
		next_permutation(a, a+4);
	}
	
	do{
		for (int i=0; i<4; i++)
			printf("%d", a[i]);
		printf("\n");
	}while (next_permutation(a, a+4));
	return 0;
}