g1201_1300.s1260_shift_2d_grid.Solution Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of leetcode-in-java21 Show documentation

Java-based LeetCode algorithm problem solutions, regularly updated

There is a newer version: 1.38

package g1201_1300.s1260_shift_2d_grid;

// #Easy #Array #Matrix #Simulation #2022_07_10_Time_6_ms_(89.10%)_Space_54.8_MB_(44.55%)

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

/**
 * 1260 - Shift 2D Grid\.
 *
 * Easy
 *
 * 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:**
 *
 * ![](https://assets.leetcode.com/uploads/2019/11/05/e1.png)
 *
 * **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:**
 *
 * ![](https://assets.leetcode.com/uploads/2019/11/05/e2.png)
 *
 * **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 Solution {
    public List> shiftGrid(int[][] grid, int k) {
        if (grid == null) {
            return Collections.emptyList();
        }
        int[] flat = new int[grid.length * grid[0].length];
        int index = 0;
        for (int[] ints : grid) {
            for (int j = 0; j < grid[0].length; ++j) {
                flat[index++] = ints[j];
            }
        }
        int mode = k % flat.length;
        int readingIndex = flat.length - mode;
        if (readingIndex == flat.length) {
            readingIndex = 0;
        }
        List> result = new ArrayList<>();
        for (int i = 0; i < grid.length; ++i) {
            List eachRow = new ArrayList<>();
            for (int j = 0; j < grid[0].length; ++j) {
                eachRow.add(flat[readingIndex++]);
                if (readingIndex == flat.length) {
                    readingIndex = 0;
                }
            }
            result.add(eachRow);
        }
        return result;
    }
}