[挑战程序设计竞赛] POJ 3187 - Backward Digit Sums

#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
#include <algorithm>
#include <iostream>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <assert.h>
#include <time.h>
//#define _Test
typedef long long LL;
const int INF = 500000001;
const double EPS = 1e-9;
const double PI = acos(-1.0);
using namespace std;
int a[10][11], flag, n, s;
bool vis[11];
bool check()
{
for(int i = 1; i < n; i++)
{
for(int j = 0; j < n-i; j++)
{
a[i][j] = a[i-1][j] + a[i-1][j+1];
}
}
return a[n-1][0] == s;
}
void dfs(int deep)
{
if(deep == n && check() && flag)
{
flag = 0;
for(int i = 0; i < n; i++)
{
printf(i?" %d":"%d", a[0][i]);
}
puts("");
return ;
}
for(int i = 1; i <= n; ++i)
{
if(flag && vis[i])
{
vis[i] = false;
a[0][deep] = i;
dfs(deep + 1);
vis[i] = true;
}
}
}
int main()
{
#ifdef _Test
freopen("test0.in", "r", stdin);
freopen("test0.out", "w", stdout);
srand(time(NULL));
#endif
while(~scanf("%d %d", &n, &s))
{
flag = 1;
memset(vis, true, sizeof(vis));
dfs(0);
}
return 0;
}