Pattern 3 (Inferred): 1. Rotate Image

Description: You are given an n x n 2D matrix representing an image, rotate the image by 90 degrees (clockwise).

Java

public void rotate(int[][] matrix)
{ int n = matrix.length;
for (int i = 0; i < n / 2; i++) {
for (int j = i; j < n - i - 1; j++)
{ int temp = matrix[i][j];
matrix[i][j] = matrix[n - j - 1][i];
matrix[n - j - 1][i] = matrix[n - i - 1][n - j - 1];
matrix[n - i - 1][n - j - 1] = matrix[j][n - i - 1];
matrix[j][n - i - 1] = temp;
}
}
}

C++

void rotate(vector<vector<int>>& matrix)
{ int n = matrix.size();
for (int i = 0; i < n / 2; i++) {
for (int j = i; j < n - i - 1; j++)
{ int temp = matrix[i][j];
matrix[i][j] = matrix[n - j - 1][i];
matrix[n - j - 1][i] = matrix[n - i - 1][n - j - 1];
matrix[n - i - 1][n - j - 1] = matrix[j][n - i - 1];
matrix[j][n - i - 1] = temp;
}
}
}

Python

def rotate(matrix):

n = len(matrix) for i in range(n // 2): for j in range(i, n - i - 1): temp = matrix[i][j] matrix[i][j] = matrix[n - j - 1][i] matrix[n - j - 1][i] = matrix[n - i - 1][n - j - 1] matrix[n - i - 1][n - j - 1] = matrix[j][n - i - 1] matrix[j][n - i - 1] = temp