区间DP，破环成链

#include <bits/stdc++.h>
using namespace std;
const int N = 410, INF = 0x3f3f3f3f, MOD = 1E9 + 7;
int n, w[N], s[N], f[N][N], g[N][N];

int main() {
    cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> w[i], w[i + n] = w[i];
    }
    for (int i = 1; i <= 2 * n; i++)
        s[i] = s[i - 1] + w[i];
    memset(f, 0x3f, sizeof f);
    memset(g, -0x3f, sizeof g);
    for (int len = 1; len <= n; len++)
        for (int l = 1; l + len - 1 <= 2 * n; l++) {
            int r = l + len - 1;
            if (len == 1) {
                f[l][r] = g[l][r] = 0; continue;
            }
            for (int k = l; k < r; k++) {
                f[l][r] = min(f[l][r], f[l][k] + f[k + 1][r] + s[r] - s[l - 1]);
                g[l][r] = max(g[l][r], g[l][k] + g[k + 1][r] + s[r] - s[l - 1]);
            }
        }
    int minv = INF, maxv = -INF;
    for (int i = 1; i <= n; i++) {
        minv = min(minv, f[i][i + n - 1]);
        maxv = max(maxv, g[i][i + n - 1]);
    }
    cout << minv << endl << maxv;
    return 0;
}