[feat ]: leetcode 463

Signed-off-by: Bo-Wei Chen(BWbwchen) <tim.chenbw@gmail.com>

Author: BWbwchen

leetcode/0463_Island-Perimeter.cpp

@@ -0,0 +1,57 @@
+class Solution {
+public:
+    vector<vector<bool>> visited;
+    vector<pair<int, int>> ops;
+    int island;
+    int neigh;
+    int max_i;
+    int max_j;
+    int islandPerimeter(vector<vector<int>>& grid) {
+        visited = vector<vector<bool>>(grid.size(), vector<bool>(grid[0].size(), false));
+        max_i = grid.size();
+        max_j = grid[0].size();
+        island = 0;
+        neigh = 0;
+        ops = {
+            make_pair(-1, 0),
+            make_pair(1, 0),
+            make_pair(0, -1),
+            make_pair(0, 1),
+        };
+        for (int i = 0; i < grid.size(); ++i) {
+            for (int j = 0; j < grid[i].size(); ++j) {
+                if (!visited[i][j])
+                    bfs(grid, i, j);
+            }
+        }
+        cout << "island: " << island << ", neigh: " << neigh << endl;
+        return island * 4 - neigh;
+    }
+    bool legal(int i, int j) {
+        return i >= 0 && i < max_i && j >= 0 && j < max_j;
+    }
+    void bfs(vector<vector<int>>& grid, int i, int j) {
+        queue<pair<int, int>> q;
+        q.push(make_pair(i, j));
+        while(!q.empty()) {
+            auto top = q.front();
+            q.pop();
+            if (legal(top.first, top.second) && !visited[top.first][top.second]) {
+                visited[top.first][top.second] = true;
+                if (grid[top.first][top.second]) {
+                    island++;
+                    for (auto op: ops) {
+                        int new_i = top.first + op.first;
+                        int new_j = top.second + op.second;
+                        if (legal(new_i, new_j)) {
+                            cout << new_i << ", " << new_j << endl;
+                            q.push(make_pair(new_i, new_j));
+                            if (grid[new_i][new_j])
+                                neigh++;
+                        }
+                    }
+                }
+            }
+        }
+    }
+};