u

Signed-off-by: xtex <xtexchooser@duck.com>

luogu/P8817.cpp

@@ -0,0 +1,107 @@
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <iostream>
+
+using namespace std;
+
+int n, m, k;
+int al;
+int *sc;
+int *pt;
+int *ps;
+
+int main() {
+  int i, x, y, l;
+
+  cin >> n >> m >> k;
+  al = (n + 1);
+  sc = (int *)malloc(sizeof(int) * al);
+  sc[1] = 0;
+  pt = (int *)malloc(sizeof(int) * (al + 1) * (al + 1));
+  ps = (int *)malloc(sizeof(int) * (al + 1) * (al + 1));
+  for (i = 0; i < (al * al); i++) {
+    pt[i] = 0xffff;
+    ps[i] = 0;
+  }
+  for (i = 2; i <= n; i++) {
+    cin >> sc[i];
+  }
+  /*for (i = 0; i <= n; i++) {
+    pt[n * al + n] = 0;
+  }*/
+  for (i = 0; i < m; i++) {
+    int a, b;
+    cin >> a >> b;
+    pt[a * al + b] = 0;
+    pt[b * al + a] = 0;
+  }
+  // 可以用BFS重写
+  for (i = 0; i <= k; i++) {
+    for (x = 0; x < al; x++) {
+      for (y = 0; y < al; y++) {
+        if (x != y && pt[x * al + y] == i) {
+          // x to y possible
+          // extend all routes
+          for (l = 0; l < al; l++) {
+            if (y != l && pt[y * al + l] != 0xffff) {
+              pt[x * al + l] = min(pt[x * al + l], pt[y * al + l] + i + 1);
+            }
+          }
+        }
+      }
+    }
+  }
+  /*for (x = 1; x < al; x++) {
+    for (y = 1; y < al; y++) {
+      cout << pt[x * al + y] << " ";
+    }
+    cout << "\n";
+  }*/
+  for (x = 0; x < al; x++) {
+    for (y = 0; y < al; y++) {
+      pt[x * al + y] = pt[x * al + y] <= k;
+    }
+  }
+  /*cout << "---\n";
+  for (x = 1; x < al; x++) {
+    for (y = 1; y < al; y++) {
+      cout << pt[x * al + y] << " ";
+    }
+    cout << "\n";
+  }*/
+  /*for (x = 1; x < al; x++) {
+    for (y = 1; y < al; y++) {
+      cout << pt[x * al + y] << " ";
+    }
+    cout << "\n";
+  }*/
+  int a, b, c, d;
+  int scs = -1;
+  for (a = 0; a < al; a++) {
+    if (!pt[1 * al + a])
+      continue;
+    for (b = 0; b < al; b++) {
+      if (a == b || !pt[a * al + b])
+        continue;
+      for (c = 0; c < al; c++) {
+        if (c == a || c == b || !pt[b * al + c])
+          continue;
+        for (d = 0; d < al; d++) {
+          if (d == a || d == b || d == c || !pt[c * al + d] || !pt[d * al + 1])
+            continue;
+          int s = sc[a] + sc[b] + sc[c] + sc[d];
+          if (s == 30) {
+            // printf("%d %d %d %d\n", a, b, c, d);
+          }
+          scs = max(scs, s);
+        }
+      }
+    }
+  }
+  cout << scs;
+  free(sc);
+  free(pt);
+  free(ps);
+  return 0;
+}