Number Of Islands

Problem Link - https://leetcode.com/problems/number-of-islands/

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Solution

    class Solution {
        public:
            void travel_island(vector<vector<char>>& grid, int r, int c,vector<vector<int>>& visited) {
                visited[r][c] = true;
                int row[] = {-1, 1, 0, 0};
                int col[] = {0, 0, -1, 1};
                for(int i = 0; i < 4; i++) {
                    if(r + row[i] < grid.size() && c + col[i] < grid[0].size() && !visited[r + row[i]][c + col[i]] && grid[r + row[i]][c + col[i]] == '1') {
                        travel_island(grid, r + row[i], c + col[i], visited);
                    }
                }
            }
            
            int numIslands(vector<vector<char>>& grid) {
                int count = 0;
                vector<vector<int>> visited;
                
                for(int i = 0; i < grid.size(); i++) {
                    vector<int> a;
                    for(int j = 0; j < grid[i].size(); j++) {  
                        a.push_back(0);
                    }
                    visited.push_back(a);
                }
                for(int i = 0; i < grid.size(); i++) {
                    for(int j = 0; j < grid[i].size(); j++) {
                        if(!visited[i][j] && grid[i][j] == '1') {
                            travel_island(grid, i, j, visited);
                            count++;
                        }
                    }
                }
                return count;
            }
        };