[LeetCode] 566.Reshape the Matrix

[LeetCode] 566.Reshape the Matrix

• 题目描述
• 解题思路
• 实验代码

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题目描述

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:
Input:
nums =
[[1,2],
[3,4]]
r = 1, c = 4
Output:
[[1,2,3,4]]
Explanation:
The row-traversing of nums is [1,2,3,4]. The new reshaped matrix is a 1 * 4 matrix, fill it row by row by using the previous list.

Example 2:
Input:
nums =
[[1,2],
[3,4]]
r = 2, c = 4
Output:
[[1,2],
[3,4]]
Explanation:
There is no way to reshape a 2 * 2 matrix to a 2 * 4 matrix. So output the original matrix.

Note:
1. The height and width of the given matrix is in range [1, 100].
2. The given r and c are all positive.

解题思路

这道题主要是找到新生成的矩阵和原来矩阵的关系，解决这道题需要先进行判断，看新的行乘列是不是等于旧矩阵的行乘列，之后就根据关系运算将旧矩阵的元素放在新矩阵对应的位置就能解决这道题。

实验代码

class Solution {
public:
    vector<vector<int>> matrixReshape(vector<vector<int>>& nums, int r, int c) {
        int m = nums.size(), n = nums[0].size();
        if (m*n != r*c)
            return nums;
        vector<vector<int>> mat(r, vector<int>(c, 0));
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                mat[(i*n+j)/c][(i*n+j)%c] = nums[i][j];
            }
        }
        return mat;
    }
};