algorithm里全是好东西

$next_permutation$真的太好用了

#include<stdio.h>
#include<algorithm>
int main(){
    int n;
    int a[15];
    scanf("%d",&n);
    for(int i=1;i<=n;i++) a[i]=i;
    do{
        for(int i=1;i<=n;i++) printf("%5d",a[i]);
        printf("\n");
    }while(std::next_permutation(a+1,a+1+n));
    return 0;
}