PROBLEM DESCRIPTION
Given two integers M, N, and a 2D matrix Mat of dimensions MxN, clockwise rotate the elements in it.
SOLUTION
- We handle the matrix layer by layer, starting by defining the top, bottom, left, and right boundaries, which will keep updating as we move inward to the inner layers.
- The main idea is to store the element just below the top-left corner for rotation and use that while swapping with other elements.
- First, store
arr[topRow+1][leftColumn]in aprevvariable. - Next, iterate from
leftColumntorightColumn.
For each position:- save the current value in a
tempvariable - place
previn the current position - update
prevto the current element to be used for the next position.
- save the current value in a
- Do the same for other side as well, right, bottom and left.
- Keep repeating for remaining layers.
- First, store
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
class Solution {
int[][] rotateMatrix(int n, int m, int arr[][]) {
int top = 0;
int bottom = n - 1;
int left = 0;
int right = m - 1;
// Loop until we finish rotating all layers
while (top < bottom && left < right) {
// Store the element just below the top-left corner for rotation
int prev = arr[top + 1][left];
// Rotate the top row from left to right
for (int c = left; c <= right; c++) {
// Temporarily store the current element
int temp = arr[top][c];
// Replace current element with the previous element
arr[top][c] = prev;
// Update prev to hold the current element for the next iteration
prev = temp;
}
// Rotate the right column from top to bottom
for (int r = top + 1; r <= bottom; r++) {
// Temporarily store the current element
int temp = arr[r][right];
// Replace current element with the previous element
arr[r][right] = prev;
// Update prev to hold the current element for the next iteration
prev = temp;
}
// Rotate the bottom row from right to left
for (int c = right - 1; c >= left; c--) {
// Temporarily store the current element
int temp = arr[bottom][c];
// Replace current element with the previous element
arr[bottom][c] = prev;
// Update prev to hold the current element for the next iteration
prev = temp;
}
// Rotate the left column from bottom to top
for (int r = bottom - 1; r >= top + 1; r--) {
// Temporarily store the current element
int temp = arr[r][left];
// Replace current element with the previous element
arr[r][left] = prev;
// Update prev to hold the current element for the next iteration
prev = temp;
}
top++;
bottom--;
left++;
right--;
}
return arr;
}
}