566. Reshape the Matrix

發表於 | 分類於

problem

solution

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

    analysis

  • time complexity O(n)
  • space complexity O(1)