Print the largest corner element in a 2-D matrix-CodePudding

I am trying to write a program which prints the number of the largest corner element in 2d array.So far I have written a code, it works with many different imputs, but I'm really stuck with this one and I'm not sure how to fix it.

The code:

#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;
int main()
{
  int n;              
  int m;                
  int a[10][10];       
    int max=0;
  cin>>n>>m;

  for(int i=0;i<n;i  ){
    for(int j=0;j<m;j  ){ 
      cin>>a[i][j];}
  }
  
  int topLeft=a[0][0];
  
  int topRight=a[0][m - 1];
  
  int lowRight=a[n - 1][m - 1];
  
  int lowLeft=a[n - 1][0];
  
 
  for(int i=0;i<n;i  ){
    for(int j=0;j<m;j  ){
        if(topLeft > topRight && topLeft > lowRight && topLeft > lowLeft){
            max=topLeft;
        }
        else if(topRight > topLeft && topRight > lowRight && topRight > lowLeft){
        max=topRight;
        }
        else if(lowRight > topLeft && lowRight > topRight && lowRight > lowLeft){
        max=lowRight; 
        }
        else if(lowLeft > topLeft && lowLeft > topRight && lowLeft > lowRight){
        max=lowLeft; 
        }
        else if(m<=1){
        max=topLeft;
        }
        else if(n<=1){
            max=topRight;
        }
        
    }
}
    cout<<""<<max<<endl;
    
  
    
return 0;
}

when I input:

it prints:

"6" instead of "9"

I've tried many different inputs, but I'm stick with this one..

CodePudding user response：

I believe you don't need the whole second part of your code. I mean, assume that being a 2D array, the angles are always 4. You just load them into a vector and find the maximum element. I hope I have not misunderstood the problem. Below, find the code.

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main() {
    int n, m;
    int a[10][10];
    
    cin >> n >> m;
    
    for(int i=0;i<n;i  ){
        for(int j=0;j<m;j  ){ 
          cin >> a[i][j];
        }
    }
    
    vector<int> corner = {a[0][0], a[0][m - 1], a[n - 1][m - 1], a[n - 1][0]};
    int maxEl = corner[0];
    
    for(unsigned i = 1; i < corner.size(); i  )
        maxEl = max(maxEl, corner[i]);
    
    cout << "Max: " << maxEl << endl;
    
    return 0;
}