48. Rotate Image

Brute force approach


Runtime    0 ms
Beats      100%


Memory     41.5 MB
Beats      33.39%


class Solution {
    public void rotate(int[][] old) {
        int [][]current=new int[old.length][old[0].length];

        for (int i = 0; i < old.length; i++)
            for (int j = 0; j < old[0].length; j++)
                current[i][j] = old[i][j] ;
        
        int a=old.length-1;

        for(int i=0;i<old.length;i++){
            for(int j=0;j<old[i].length;j++){
                old[j][a]=current[i][j];
            }
            a--;
        }
    }
}


Optizmed approach

Runtime   0 ms
Beats     100%


Memory   41.2 MB
Beats    79.25%


class Solution {
    static void reverseArray(int [] arr)
        {
            int i=0;int j= arr.length-1;
            while (i<j)
            {
                int temp =arr[i];
                arr[i]=arr[j];
                arr[j]=temp;

                i++;
                j--;
            }
        }
    public void rotate(int[][] old) {
        int temp=0;
        for(int i=0;i<old.length-1;i++){
            for(int j=i+1;j<old.length;j++){
                temp=old[i][j];
                old[i][j]=old[j][i];
                old[j][i]=temp;
            }
        }
        for(int i=0;i<old.length;i++){
            reverseArray(old[i]);
        }
    }
}