(LEETCODE)Number-of-Islands

Author: Gaurav Sood

Graph/(LEETCODE)Number-of-Islands.cpp

@@ -0,0 +1,32 @@
+class Solution {
+public:
+    void dfs(vector<vector<char>>& grid,vector<vector<bool>> &visited,int r, int c){
+        static int dirX[] = { -1, 0 , 0 , 1 }; 
+        static int dirY[] = { 0 , 1 , -1, 0 }; 
+        visited[r][c] = true;
+        for(int i = 0 ; i < 4 ; ++i){
+            int nextr = r + dirX[i];
+            int nextc = c + dirY[i];
+            if(nextr >= 0 && nextr < grid.size() && nextc >= 0 && nextc < grid[0].size() && grid[nextr][nextc] == '1' &&  !visited[nextr][nextc]){
+                dfs(grid,visited,nextr,nextc);
+            }
+        }
+    }
+    
+    int numIslands(vector<vector<char>>& grid) {
+        int m = grid.size();
+        if(m == 0) return 0;
+        int n = grid[0].size();
+        int cnt = 0;
+        vector<vector<bool> > visited(m, vector<bool>(n,false));
+        for(int i = 0 ; i < m ; ++i){
+            for(int j = 0; j < n; ++j){
+                if(grid[i][j] == '1' && !visited[i][j]){
+                    dfs(grid,visited,i,j);
+                    ++cnt;        
+                }
+            }
+        }
+        return cnt;
+    }
+};