P3092 [USACO13NOV]No Change G

https://www.luogu.com.cn/record/76702320

Luogu/P3092/P3092.cpp

@@ -0,0 +1,69 @@
+#include <iostream>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 100005;
+
+int n, k, w[16], sum[N], f[0xffff + 5], ans;
+bool flag;
+
+int find(int x, int y) {
+    int l = f[x],
+        r = std::min(n, f[x] + w[y]);  // 优化：每个物品的最小价值为 1
+    int res = l;
+
+    while (l <= r) {
+        int mid = l + r >> 1;
+        if (sum[mid] - sum[f[x]] <= w[y]) {
+            res = mid;
+            l = mid + 1;
+        } else {
+            r = mid - 1;
+        }
+    }
+
+    return res;
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+
+    cin >> k >> n;
+
+    for (int i = 0; i < k; i++) {
+        cin >> w[i];
+    }
+
+    for (int i = 1, x; i <= n; i++) {
+        cin >> x;
+        sum[i] = sum[i - 1] + x;
+    }
+
+    for (int i = 0; i < 1 << k; i++) {
+        for (int j = 0; j < k; j++) {
+            if ((i >> j) & 1) continue;
+            f[i | (1 << j)] = std::max(f[i | (1 << j)], find(i, j));
+        }
+
+        if (f[i] == n) {  // 全部购买完
+            flag = true;
+            int cnt = 0;
+
+            for (int j = 0; j < k; j++) {
+                if (!((i >> j) & 1)) cnt += w[j];
+            }
+
+            ans = std::max(ans, cnt);
+        }
+    }
+
+    if (flag) {
+        cout << ans << endl;
+    } else {
+        cout << -1 << endl;
+    }
+
+    return 0;
+}