/** ================================================== * Function: return the number of islands * * @param {character[][]} grid * @return {number} =================================================== */ var numIslands = function(grid) { let count = 0; for (let i = 0; i < grid.length; i++) { for (let j = 0; j < grid[i].length; j++) { if grid[i][j] == "1") { count = count + dfs(grid,i,j); } } } function dfs(grid,row,col) { // base cases if (row < 0 || row > grid.length-1 || col < 0 || col > grid[row].length-1 || grid[row][col] == "0") { return; } grid[row][col] = "0" dfs(grid,row+1,col); dfs(grid,row-1,col); dfs(grid,row,col+1); dfs(grid,row,col-1); return 1; } return count; };