3312. [USACO2013 Nov] No Change

https://hydro.ac/d/bzoj/record/6322eb3d32ae6c3198cc9a01

BZOJ/3312/3312.cpp

@@ -0,0 +1,69 @@
+#include <iostream>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 100005;
+
+int k, n, w[20], s[N], f[1 << 17], ans;
+bool flag;
+
+inline int find(int x, int y) {
+    int l = f[x],
+        r = std::min(n, f[x] + w[y]);
+
+    int res = l;
+    while (l <= r) {
+        int mid = l + r >> 1;
+
+        if (s[mid] - s[f[x]] <= w[y]) {
+            res = mid;
+            l = mid + 1;
+        } else {
+            r = mid - 1;
+        }
+    }
+
+    return res;
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> k >> n;
+
+    for (int i = 0; i < k; i++) {
+        cin >> w[i];
+    }
+
+    for (int i = 1, x; i <= n; i++) {
+        cin >> x;
+
+        s[i] = s[i - 1] + x;
+    }
+
+    for (int i = 0; i < 1 << k; i++) {
+        for (int j = 0; j < k; j++) {
+            if (!(i & (1 << j))) {
+                f[i | (1 << j)] = std::max(f[i | (1 << j)], find(i, j));
+            }
+        }
+
+        if (f[i] == n) {
+            flag = true;
+
+            int sum = 0;
+            for (int j = 0; j < k; j++) {
+                if (!(i & (1 << j))) sum += w[j];
+            }
+
+            ans = std::max(ans, sum);
+        }
+    }
+
+    cout << (flag ? ans : -1) << endl;
+
+    return 0;
+}