NYOJ19 擅长排列的小明【next_permutation】

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;
}