463-Island_ Perimeter.html

<html>
<script>

var islandPerimeter = function(grid) {
    let land = 0;
    let overlapEdge = 0;
    for(let i = 0; i < grid.length; i++){
        for(let j = 0; j < grid[0].length; j++){
            if(grid[i][j] === 1){
                land ++;                
                if((i-1) >=0 && grid[i-1][j] === 1){
                    overlapEdge++;    
                }
                if((j-1) >= 0 && grid[i][j-1] === 1){
                    overlapEdge++;    
                }
                if((i+1) < grid.length && grid[i+1][j] === 1){
                    overlapEdge++;    
                }
                if((j+1) < grid[0].length && grid[i][j+1] === 1){
                    overlapEdge++;    
                }
            }
        }
    }
    return land*4 - overlapEdge;
};

islandPerimeter([[0,1,0,0],[1,1,1,0],[0,1,0,0],[1,1,0,0]]);
</script>
</html>