grid.length --- to get the number of rows grid[0].length ---- to get the number of cols
From https://leetcode.com/problems/island-perimeter/#/description
public class Solution {
public int islandPerimeter(int[][] grid) {
int per = 0;
for (int i =0; i< grid.length ; i++){ // grid.length to get the number of rows
for(int j =0; j< grid[0].length; j++){ // grid[0].length to get the number of cols
if (grid[i][j] == 1){
per = per + 4;
if( i != grid.length -1 && grid[i+1][j] == 1){
per--;
}
if ( j != 0 && grid[i][j-1] == 1){
per--;
}
if ( j != grid[0].length - 1 && grid[i][j+1] ==1 ){
per--;
}
if( i != 0 && grid[i-1][j] ==1 ){
per--;
}
}
}
}
return per;
}
}