poj3628

dfs

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

#define maxn 25

int n, m;
int f[maxn], s[maxn];
int ans;

void dfs(int cow, int sum)
{
    if (ans == 0)
        return;
    if (s[cow] + sum < m)
        return;
    if (sum >= m)
    {
        ans = min(ans, sum - m);
        return;
    }
    if (cow == n)
        return;
    dfs(cow + 1, sum);
    dfs(cow + 1, sum + f[cow]);
}

int main()
{
    //freopen("t.txt", "r", stdin);
    scanf("%d%d", &n, &m);
    for (int i = 0; i < n; i++)
        scanf("%d", &f[i]);
    s[n] = 0;
    for (int i = n - 1; i >= 0; i--)
        s[i] = s[i + 1] + f[i];
    ans = 0x3f3f3f3f;
    dfs(0, 0);
    printf("%d\n", ans);
    return 0;
}