学步园

原题链接

next_permutation若返回false，则将数组置为字典序最小值。

#include <cstdio>
#include <algorithm>
using namespace std;
char samp[] = {'1', '2', '3', '4', '5', '6', '7', '8', '9'};
char str[10];

int main(){
	int t, n, m, i;
	scanf("%d", &t);
	while(t--){
		scanf("%d%d", &n, &m);
		do{
			if(!equal(samp, samp + m, str)){
				copy(samp, samp + m, str);
				for(i = 0; i < m; ++i) putchar(str[i]);
				putchar('\n');
			}
		}while(next_permutation(samp, samp + n));
	}
	return 0;
}

800707

长木

擅长排列的小明

Accepted

32

232

C/C++

04-07 16:25:32

方法二：DFS

#include <stdio.h>
#include <string.h>

int n, m, id;
bool arr[10];
int store[10];

void print(){
	for(int i = 1; i <= m; ++i)
		printf("%d", store[i]);
	printf("\n");
}

void DFS(){
	if(id == m){
		print();
		return;
	}
	for(int i = 1; i <= n; ++i){
		if(!arr[i]){
			store[++id] = i;
			arr[i] = 1;
			DFS();
			--id;
			arr[i] = 0;
		}
	}
}

int main(){
	int t;
	scanf("%d", &t);
	while(t--){
		scanf("%d%d", &n, &m);
		DFS();		
		memset(arr, 0, sizeof(arr));
		id = 0;
	}
	return 0;
}