Question

How to rotate a matrix 90 degrees clockwise in TypeScript

Answer 1

function rotate90Clockwise(matrix: number[][]): void {
    let N: number = matrix.length;

    // Step 1: Transpose the matrix
    for (let i: number = 0; i < N; i++) {
        for (let j = i; j < N; j++) {
            [matrix[i][j], matrix[j][i]] = [matrix[j][i], matrix[i][j]];
        }
    }

    // Step 2: Reverse each row
    for (let i: number = 0; i < N; i++) {
        matrix[i].reverse();
    }
}

function printMatrix(matrix: number[][]): void {
    matrix.forEach(row => console.log(row.join(" ")));
}

let matrix: number[][] = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
];

console.log("Original Matrix:");
printMatrix(matrix);

rotate90Clockwise(matrix);

console.log("\nRotated Matrix:");
printMatrix(matrix);


  
  
/*
run:
  
"Original Matrix:" 
"1 2 3" 
"4 5 6" 
"7 8 9" 

"Rotated Matrix:" 
"7 4 1" 
"8 5 2" 
"9 6 3" 
  
*/

 

70+ SQL courses for beginners and professionals

Answer 2

function rotate90Clockwise(matrix: number[][]): number[][] {
    let rows: number = matrix.length;
    let cols: number = matrix[0].length;
    
    let rotated: number[][] = Array.from({ length: cols }, () => Array(rows).fill(0));

    for (let i: number = 0; i < rows; i++) {
        for (let j: number = 0; j < cols; j++) {
            rotated[j][rows - 1 - i] = matrix[i][j]; // Mapping to rotated position
        }
    }

    return rotated;
}

function printMatrix(matrix: number[][]): void {
    matrix.forEach(row => console.log(row.join(" ")));
}

let matrix: number[][] = [
    [1, 2, 3, 4],
    [5, 6, 7, 8],
    [9, 10, 11, 12]
];

console.log("Original Matrix:");
printMatrix(matrix);

let rotated: number[][] = rotate90Clockwise(matrix);

console.log("\nRotated Matrix:");
printMatrix(rotated);

  
  
/*
run:
  
"Original Matrix:" 
"1 2 3 4" 
"5 6 7 8" 
"9 10 11 12" 

"Rotated Matrix:" 
"9 5 1" 
"10 6 2" 
"11 7 3" 
"12 8 4" 
  
*/

 

70+ SQL courses for beginners and professionals