Update maximum-number-of-moves-to-kill-all-pawns.cpp

Author: kamyu104

C++/maximum-number-of-moves-to-kill-all-pawns.cpp

@@ -30,26 +30,28 @@ class Solution {
             }
             return dist;
         };
-    
-        vector<vector<int>> dist(size(positions), vector<int>(size(positions)));
-        for (int i = 0; i < size(positions); ++i) {
+
+        const int p = size(positions);
+        positions.emplace_back(vector<int>{kx, ky});
+        vector<vector<int>> dist(p + 1, vector<int>(p + 1));
+        for (int i = 0; i <= p; ++i) {
             const auto& d = bfs(positions[i][0], positions[i][1]);
-            for (int j = i + 1; j < size(positions); ++j) {
+            for (int j = i + 1; j <= p; ++j) {
                 dist[j][i] = dist[i][j] = d[positions[j][0]][positions[j][1]];
             }
         }
-        vector<vector<int>> dp(1 << size(positions));
-        for (int mask = 1; mask < 1 << size(positions); ++mask) {
-            dp[mask].assign(size(positions), __builtin_popcount(mask) & 1 ? POS_INF : NEG_INF);
+        vector<vector<int>> dp(1 << p);
+        for (int mask = 1; mask < 1 << p; ++mask) {
+            dp[mask].assign(p, __builtin_popcount(mask) & 1 ? POS_INF : NEG_INF);
         }
-        dp.back().assign(size(positions), 0);
-        for (int mask = (1 << size(positions)) - 1; mask >= 1; --mask) {
+        dp.back().assign(p, 0);
+        for (int mask = (1 << p) - 1; mask >= 1; --mask) {
             const auto& turn = (__builtin_popcount(mask) & 1) ^ 1;
-            for (int i = 0; i < size(positions); ++i) {
+            for (int i = 0; i < p; ++i) {
                 if ((mask & (1 << i)) == 0) {
                     continue;
                 }
-                for (int j = 0; j < size(positions); ++j) {
+                for (int j = 0; j < p; ++j) {
                     if (j == i || (mask & (1 << j)) == 0) {
                         continue;
                     }
@@ -59,9 +61,8 @@ class Solution {
             }
         }
         int result = 0;
-        const auto& d = bfs(kx, ky);
-        for (int i = 0; i < size(positions); ++i) {
-            result = max(result, dp[1 << i][i] + d[positions[i][0]][positions[i][1]]);
+        for (int i = 0; i < p; ++i) {
+            result = max(result, dp[1 << i][i] + dist[i][p]);
         }
         return result;
     }