[USACO 2012 Jan Silver] Bale Share【DP】

#include <cstdio>

const int maxn = 21;

int n, a, s, ans = 2147483647;
bool f[2005][2005];

inline int minn(int aa, int ss) {
    return aa < ss? aa: ss;
}
inline int max3(int aa, int ss, int dd) {
    aa = aa > dd? aa: dd;
    return aa > ss? aa: ss;
}

int main(void) {
    freopen("baleshare.in", "r", stdin);
    freopen("baleshare.out", "w", stdout);
    scanf("%d", &n);
    f[0][0] = true;
    for (int i = 1; i <= n; ++i) {
        scanf("%d", &a);
        s += a;
        for (int j = s; j >= 0; --j) {
            for (int k = s - j; k >= 0; --k) {
                if (j >= a) {
                    f[j][k] = f[j][k] || f[j - a][k];
                }
                if (k >= a) {
                    f[j][k] = f[j][k] || f[j][k - a];
                }
            }
        }
    }
    
    for (int j = 0; j <= s; ++j) {
        for (int k = 0; j + k <= s; ++k) {
            if (f[j][k]) {
                ans = minn(ans, max3(j, k, s - j - k));
            }
        }
    }
    printf("%d\n", ans);
    return 0;
}