1260. Shift 2D Grid

Description

Given a 2D grid of size m x n and an integer k. You need to shift the grid k times.

In one shift operation:

• Element at grid[i][j] moves to grid[i][j + 1].
• Element at grid[i][n - 1] moves to grid[i + 1][0].
• Element at grid[m - 1][n - 1] moves to grid[0][0].

Return the 2D grid after applying shift operation k times.

 

Example 1:

Input: grid = [[1,2,3],[4,5,6],[7,8,9]], k = 1
Output: [[9,1,2],[3,4,5],[6,7,8]]

Example 2:

Input: grid = [[3,8,1,9],[19,7,2,5],[4,6,11,10],[12,0,21,13]], k = 4
Output: [[12,0,21,13],[3,8,1,9],[19,7,2,5],[4,6,11,10]]

Example 3:

Input: grid = [[1,2,3],[4,5,6],[7,8,9]], k = 9
Output: [[1,2,3],[4,5,6],[7,8,9]]

 

Constraints:

• m == grid.length
• n == grid[i].length
• 1 <= m <= 50
• 1 <= n <= 50
• -1000 <= grid[i][j] <= 1000
• 0 <= k <= 100

 

Solutions

Solution: Math

• Time complexity: O(mn)
• Space complexity: O(mn)

 

JavaScript

/**
 * @param {number[][]} grid
 * @param {number} k
 * @return {number[][]}
 */
const shiftGrid = function (grid, k) {
  const m = grid.length;
  const n = grid[0].length;
  const result = Array.from({ length: m }, () => new Array(n));

  for (let row = 0; row < m; row++) {
    for (let col = 0; col < n; col++) {
      const value = grid[row][col];
      const nextCol = col + k;
      const nextRow = Math.floor(nextCol / n) + row;

      result[nextRow % m][nextCol % n] = value;
    }
  }

  return result;
};