Algo-Trian

Algorithm/DP-DynamicProgramming/P1807 最长路.cpp

@@ -0,0 +1,42 @@
+#include <iostream>
+#include <vector>
+using namespace std;
+
+const int NEG_INF = -1e9;
+
+int main() {
+    int v, e;
+    cin >> v >> e;
+
+    vector<vector<int>> dp(v, vector<int>(v, NEG_INF));
+    for (int i = 0; i < v; i++) dp[i][i] = 0;  // <20>Ի<EFBFBD>=0
+
+    for (int i = 0; i < e; i++) {
+        int a, b, w;
+        cin >> a >> b >> w;
+        dp[a - 1][b - 1] = max(dp[a - 1][b - 1], w); // <20><><EFBFBD>ܶ<EFBFBD><DCB6><EFBFBD><EFBFBD>ߣ<EFBFBD>ȡ<EFBFBD><C8A1><EFBFBD><EFBFBD>
+    }
+
+    for (int k = 0; k < v; k++) {
+        for (int i = 0; i < v; i++) {
+            if (dp[i][k] <= NEG_INF / 2) continue;
+            for (int j = 0; j < v; j++) {
+                if (dp[k][j] <= NEG_INF / 2) continue;
+                dp[i][j] = max(dp[i][j], dp[i][k] + dp[k][j]);
+            }
+        }
+    }
+
+    int mx = -1;
+    for (int i = 0; i < v; i++) {
+        for (int j = 0; j < v; j++) {
+            if (dp[i][j] > NEG_INF / 2) {
+                mx = max(mx, dp[i][j]);
+            }
+        }
+    }
+
+    mx == -1 ? cout << mx << endl;
+    return 0;
+}
+