vault backup: 2022-07-16 08:59:20

OJ notes/pages/Leetcode Max-Area-of-Island.md

@@ -68,6 +68,11 @@ We keep track of pile we visited, using:
 - an 2-d bool vector visited(which is the one I'm using)
 - change the value of pile to 0
 
+and check for:
+- x, y is not OOB
+- x, y is in a island -> (value == 1)
+- x, y is not visited (see above)
+
 And for each unvisited pile, run DFS or BFS to check the size, and keep track of max size with a variable
 
 ### Solution
@@ -204,3 +209,44 @@ public:
 ```
 
 DFS recursive
+```cpp
+class Solution {
+  // DFS recursive
+  int getSize(vector<vector<int>> &grid, int m, int n, int x, int y,
+              vector<vector<bool>> &visited) {
+    if (x >= 0 && x < m && y >= 0 && y < n && !visited[x][y] &&
+        grid[x][y] == 1) {
+      visited[x][y] = true;
+      return 1 + getSize(grid, m, n, x + 1, y, visited) +
+             getSize(grid, m, n, x - 1, y, visited) +
+             getSize(grid, m, n, x, y + 1, visited) +
+             getSize(grid, m, n, x, y - 1, visited);
+    } else {
+      return 0;
+    }
+  }
+
+public:
+  int maxAreaOfIsland(vector<vector<int>> &grid) {
+    int m = grid.size(), n = grid[0].size();
+    int maxSize = 0;
+
+    vector<vector<bool>> visited;
+    for (int i = 0; i < m; i++) {
+      visited.push_back({});
+      for (int j = 0; j < n; j++) {
+        visited.back().push_back(false);
+      }
+    }
+
+    for (int i = 0; i < m; i++) {
+      for (int j = 0; j < n; j++) {
+        if (grid[i][j] == 1 && !visited[i][j]) {
+          maxSize = max(maxSize, getSize(grid, m, n, i, j, visited));
+        }
+      }
+    }
+    return maxSize;
+  }
+};
+```