[LeetCode | C++] July LeetCoding Challenge 2021 — Week 1 Reshape the Matrix (5th, July)

yeahsilver

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Jul 6, 2021

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📃 Problem

https://leetcode.com/explore/challenge/card/july-leetcoding-challenge-2021/608/week-1-july-1st-july-7th/3803/

💡 Check Point

1. Determine whether given values r,c are possible and legal.
2. Determine how to create a reshaped matrix from an original matrix.

👩‍💻 My Solution

class Solution {
public:

    vector<vector<int> > matrixReshape(vector<vector<int> >& mat, int r, int c) {
        vector<vector<int> > result;
		
        // Define original matrix's row and column
        // m = original row, n = original colum
        int m = mat.size();
        int n = mat[0].size();
		
        // If we could not create a reshaped matrix with using given values c, r
        // => return an origianl matrix
        if(r*c != m*n) {
            return mat;
        }

		
        // Otherwise, create a reshaped matrix!
        for(int i = 0; i < r; i++) {
            vector<int> values;

            for(int j = 0; j < c; j++) {
            	// Define k which calculate a new matrix's 1d index
                int k = c * i + j;
                
                // Calculate 2d indices using 1d index
                values.push_back(mat[k/n][k%n]);
            }

            result.push_back(values);
        }

        return result;
    }
};