var rotate = function(matrix) {
if(!matrix.length) return [];
let left = 0,right = matrix.length-1;
while(right-left > 0){
[matrix[left],matrix[right]] = [matrix[right],matrix[left]];
left++;
right--;
}
for(let i = 0;i < matrix.length;i++){
for(let j = i+1;j < matrix[i].length;j++){
[matrix[i][j],matrix[j][i]] = [matrix[j][i],matrix[i][j]];
}
}
return matrix;
};