Shift2DGrid.java

package easy;

import java.util.*;

/**
 * ClassName: Shift2DGrid.java
 * Author: chenyiAlone
 * Create Time: 2020/1/13 22:04
 * Description: No.1260 Shift 2D Grid
 *
 *
 * 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
 *
 */
public class Shift2DGrid {

    public List<List<Integer>> shiftGrid(int[][] grid, int k) {
        int n = grid.length, m = grid[0].length, len = n * m;
        Integer[][] ng = new Integer[n][m];
        k %= len;
        List<List<Integer>> ret = new ArrayList<>();
        for (int i = 0, j = k; i < len; i++, j = (j + 1) % len) {
            ng[j / m][j % m] = grid[i / m][i % m];
        }
        for (Integer[] arr : ng)
            ret.add(Arrays.asList(arr));
        return ret;
    }

}