Cows in a Skyscraper G

dfs版本

#include <algorithm>
#include <iostream>

using namespace std;

const int N = 2e1;

int cat[N], cab[N];
int n, w;
int ans;

bool cmp(int a, int b) {
    return a > b;
}

void dfs(int now, int cnt) {
    if (cnt >= ans) {
        return;
    }
    if (now == n + 1) {
        ans = min(ans, cnt);
        return;
    }
    //嘗試分配到已經租用的纜車上
    for (int i = 1; i <= cnt; i++) {  //分配到已租用纜車
        if (cab[i] + cat[now] <= w) {
            cab[i] += cat[now];
            dfs(now + 1, cnt);
            cab[i] -= cat[now];  //還原
        }
    }

    // 新開一輛纜車
    cab[cnt + 1] = cat[now];
    dfs(now + 1, cnt + 1);
    cab[cnt + 1] = 0;
}

int main() {
    cin >> n >> w;
    for (int i = 1; i <= n; i++) {
        cin >> cat[i];
    }

    sort(cat + 1, cat + 1 + n, cmp);

    ans = n;

    dfs(1, 0);

    cout << ans << endl;

    return 0;
}