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Leetcode 566 Reshape The Matrix

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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:

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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:

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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.

构造二维数组赋值

没什么难的, 没学过数据结构和算法的也能做出来, 注意要先判断给的r*c和nums的元素数量是否相同

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class Solution {
public:
    vector<vector<int>> matrixReshape(vector<vector<int>>& nums, int r, int c) {
        if(nums.size() == 0)
            return nums;
        int count = nums.size() * nums.front().size();
        if(count != r * c)
        {
            return nums;
        }
        vector<int> tmp(c,0);
        vector<vector<int>> vvc(r,tmp);
        int new_i = 0;
        int new_j = 0;
        for(const vector<int>& i : nums)
        {
            for(int j : i)
            {
                vvc[new_i][new_j] = j;
                ++new_j;
                if(new_j == c)
                {
                    new_j = 0;
                    ++new_i;
                }
            }
        }
        return vvc;
    }
};