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566. Reshape the Matrix

程序员文章站 2022-05-31 18:54:58
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In MATLAB, there is a very useful function called ‘reshape’, which can reshape a matrix into a new one with different size but keep its original data.
You’re given a matrix represented by a two-dimensional array, and two positive integers r and c representing the row number and column number of the wanted reshaped matrix, respectively.
The reshaped matrix need to be filled with all the elements of the original matrix in the same row-traversing order as they were.
If the ‘reshape’ operation with given parameters is possible and legal, output the new reshaped matrix; Otherwise, output the original matrix.
Example 1:
566. Reshape the Matrix
Example 2:
566. Reshape the Matrix


题解:
package com.leetcode;

import java.util.Arrays;

public class MatrixReshape {

public static void main(String[] args) {
    int[][] nums = { { 1, 2 }, 
                     { 3, 4 } };
    System.out.println(Arrays.deepToString(nums));

    int[][] ans = matrixReshape(nums, 4, 1);
    System.out.println(Arrays.deepToString(ans));

    ans = matrixReshape(nums, 1, 4);
    System.out.println(Arrays.deepToString(ans));


    ans = matrixReshape(nums, 2, 4);
    System.out.println(Arrays.deepToString(ans));
}

public static int[][] matrixReshape(int[][] nums, int r, int c) {
    if (r * c != nums.length * nums[0].length)
        return nums;

    int[][] ans = new int[r][];
    for (int i = 0; i < r; i++)
        ans[i] = new int[c];

    for (int i = 0; i < r; i++) {
        for (int j = 0; j < c; j++) {
            int k = i * c + j;              // ans中的第k个元素
            int a = k / nums[0].length;     // ans中的第k个元素在nums中对应的下标
            int b = k - a * nums[0].length;
            ans[i][j] = nums[a][b];
        }
    }
    return ans;
}

}

相关标签: Reshape Matrix