463. Island Perimeter

public class Solution {
    public int islandPerimeter(int[][] grid) {
        int i=0,j=0;
        int sum=0,reduce=0;
        for(i=0;i<grid.length;i++){
            for(j=0;j<grid[0].length;j++){
                if(grid[i][j]==1){
                    sum+=4;
                    if(i<grid.length-1)reduce+=grid[i+1][j]==1?2:0;
                    if(j<grid[0].length-1)reduce+=grid[i][j+1]==1?2:0;
                }
            }
        }
        sum-=reduce;
        return sum;
    }
}