1380. lucky numbers in matrices

subject

1380. The lucky number in the matrix

The main idea of the topic

To give you one m * n Matrix , The number in the matrix Each are not identical . Please press arbitrarily Return all the lucky numbers in the matrix in order .

Lucky number refers to the elements in the matrix that meet the following two conditions at the same time ：

• The smallest of all elements in the same row
• The largest of all elements in the same column

Examples

Data scale

Ideas

Definition minnr[],maxxc[] Separate indication control $i$ Row min and th $j$ The value of the largest element in the column . Preprocessing by traversing the matrix . After processing the relevant maximum values of each row and column , Traverse every element of the matrix again $matrix[i][j]$, If it can satisfy $matrix[i][j]==minnr[i]\&\&matrix[i][j]==maxxc[j]$, It means that the element is a lucky number , Add to answer array $ans$ in , Finally back to $ans$.

Code

class Solution {
    
public:
    int minnr[100],maxxc[100];
    vector<int> luckyNumbers (vector<vector<int>>& matrix) {
    
        memset(minnr,0x3f3f3f3f,sizeof(minnr));
        memset(maxxc,-0x3f3f3f3f,sizeof(maxxc));
        int n=matrix.size(),m=matrix[0].size();
        for(int i=0;i<n;i++){
    
            for(int j=0;j<m;j++){
    
                minnr[i]=min(minnr[i],matrix[i][j]);
                maxxc[j]=max(maxxc[j],matrix[i][j]);
            }
        }
        vector<int>ans;
        for(int i=0;i<n;i++){
    
            for(int j=0;j<m;j++){
    
                if(matrix[i][j]==minnr[i]&&matrix[i][j]==maxxc[j]){
    
                    ans.push_back(matrix[i][j]);
                }
            }
        }
        return ans;
    }
};