num_of_islands.js

num_of_islands.js

function dfs(grid, r, c) {
  var nr = grid.length;
  var nc = grid[0].length;

  if (r < 0 || c < 0 || r >= nr || c >= nc || grid[r][c] === '0') {
    return;
  }
  grid[r][c] = '0';

  dfs(grid, r - 1, c);
  dfs(grid, r + 1, c);
  dfs(grid, r, c - 1);
  dfs(grid, r, c + 1);
}

function numIslands(grid) {
  if (typeof grid === 'undefined' || grid.length === 0) {
    return;
  }

  var num_islands = 0;
  var nr = grid.length;
  var nc = grid[0].length;

  for (var r = 0; r < nr; r++) {
    for (var c = 0; c < nc; c++) {
      if (grid[r][c] === '1') {
        num_islands++;
        dfs(grid, r, c);
      }
    }
  }

  return num_islands;
}

var g = [["1", "1", "1", "1", "0"], ["1", "1", "0", "1", "0"], ["1", "1", "0", "0", "0"], ["0", "0", "0", "0", "0"]];

console.log(numIslands(g));
</script>



<script id="jsbin-source-javascript" type="text/javascript">function dfs(grid, r, c) {
  let nr = grid.length;
  let nc = grid[0].length;

  if (r < 0 || c < 0 || r >= nr || c >= nc || grid[r][c] === '0') {
    return;
  }
  grid[r][c] = '0';

  dfs(grid, r - 1, c);
  dfs(grid, r + 1, c);
  dfs(grid, r, c - 1);
  dfs(grid, r, c + 1);
}


function numIslands(grid) {
  if(typeof grid === 'undefined' || grid.length === 0) {
    return;
  }
  
  let num_islands = 0;
  let nr = grid.length;
  let nc = grid[0].length;
  
  for(let r = 0; r < nr; r++) {
    for (let c = 0; c < nc; c++) {
      if (grid[r][c] === '1') {
        num_islands++;
        dfs(grid, r, c);
      }
    }
  }
  
  
  return num_islands;
}

const g = [
  ["1","1","1","1","0"],
  ["1","1","0","1","0"],
  ["1","1","0","0","0"],
  ["0","0","0","0","0"]
];

console.log(numIslands(g));