[Leetcode] 566. Reshape the Matrix 解题报告

矩阵重塑算法

最新推荐文章于 2024-06-23 21:20:26 发布

原创最新推荐文章于 2024-06-23 21:20:26 发布 · 289 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#Leetcode #解题报告 #Array

IT公司面试习题专栏收录该内容

736 篇文章

订阅专栏

本文介绍了一个简单的矩阵重塑算法，该算法可以将输入的二维数组重塑为指定行数和列数的新矩阵，同时保持原有的数据顺序不变。如果重塑操作合法且可行，则输出重塑后的矩阵；否则输出原始矩阵。

题目：

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:

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

思路：

练手题目，哈哈哈。

代码：

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