Merge pull request neetcode-gh#1230 from ElminD/patch-1

Update 49-Java

java/48-Rotate-Image.java

@@ -1,35 +1,33 @@
-// Do note that this is for a sqaure matrix (NxN)
-// The process is to first transpose the matrix and then reverse it
-// Taking the first example: [[1,2,3],[4,5,6],[7,8,9]]
-// After Transpose: [[1,4,7],[2,5,8],[3,6,9]]
-// After Reversal: [[7,4,1],[8,5,2],[9,6,3]]
-
 class Solution {
-
  public void rotate(int[][] matrix) {
- int N = matrix.length;
+ int l = 0;
+ int r = matrix.length - 1;
+
+ while ( l < r )
+ {
+ for(int i = 0; i < r - l; i++)
+ {
+ int top = l;
+ int bottom = r;
+ //save the topleft
+ int topLeft = matrix[top][l + i];
 
- transpose(matrix, N);
- reverse(matrix, N);
- }
+ //move bottom left into top left
+ matrix[top][l + i] = matrix[bottom - i][l];
 
- void transpose(int[][] matrix, int n) {
- for (int i = 0; i < n; i++) {
- for (int j = i + 1; j < n; j++) {
- int temp = matrix[j][i];
- matrix[j][i] = matrix[i][j];
- matrix[i][j] = temp;
- }
- }
- }
+ // move bottom right into bottom left
+ matrix[bottom - i][l] = matrix[bottom][r - i];
+
+ // move top right into bottom right
+ matrix[bottom][r - i] = matrix[top + i][r];
 
- void reverse(int[][] matrix, int n) {
- for (int i = 0; i < n; i++) {
- for (int j = 0; j < n / 2; j++) {
- int temp = matrix[i][j];
- matrix[i][j] = matrix[i][n - 1 - j];
- matrix[i][n - 1 - j] = temp;
+ // move top left into top right
+ matrix[top + i][r] = topLeft;
+
  }
+
+ r -= 1;
+ l += 1;
  }
  }
 }