'commit'

TangDou/AcWing/Section/1069_dfs.cpp

@@ -0,0 +1,54 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+const int N = 50 + 10;
+
+//__int128专用
+typedef __int128 LL;
+const LL INF = 1e38;
+LL read() { // 快读
+    LL x = 0, f = 1;
+    char ch = getchar();
+    while (ch < '0' || ch > '9') {
+        if (ch == '-') f = -1;
+        ch = getchar();
+    }
+    while (ch >= '0' && ch <= '9') {
+        x = x * 10 + ch - '0';
+        ch = getchar();
+    }
+    return x * f;
+}
+void write(LL x) { // 快写
+    if (x < 0) putchar('-'), x = -x;
+    if (x > 9) write(x / 10);
+    putchar(x % 10 + '0');
+}
+
+LL w[N];
+LL f[N][N];
+
+// 计算[l,r]之间的三角剖分最大值
+LL dfs(int l, int r) {
+    LL &v = f[l][r];
+    if (v != INF) return v;         // 记忆化
+    if (r - l < 2) return v = 0;    // 不够三个点，哪来的剖分值
+    for (int k = l + 1; k < r; k++) // 中间点k不能与l,r重合
+        v = min(v, dfs(l, k) + dfs(k, r) + w[l] * w[r] * w[k]);
+    return v;
+}
+
+int main() {
+    int n;
+    scanf("%d", &n);
+    for (int i = 1; i <= n; i++) w[i] = read();
+
+    // 初始化极值
+    for (int i = 1; i <= n; i++)
+        for (int j = 1; j <= n; j++)
+            f[i][j] = INF;
+
+    write(dfs(1, n));
+    return 0;
+}