全为 1 的最大尺寸矩形二进制子矩阵

Question

I wrote this code with the histogram solution but instead of entering the matrix on the code, the user will input its matrix. now idk what I'm doing wrong, everything seems to work except the math of the histogram. What am I doing wrong?

The user will input the rows and columns, then one by one, each value in the matrix. then the code will show the matrix and calculate the Maximum size rectangle binary sub-matrix with all 1s.

#include <stdio.h>
#include <bits/stdc++.h>
#include <iostream>

using namespace std;
 
#define MAXROW      100
#define MAXCOL      100
 
int maxHist(int row[]){
        stack<int> result; 
    int top_val;
    int max_area = 0;
    int area = 0; 
    int a = 0; 
    while (a < MAXCOL) 
   { 
       if (result.empty() || row[result.top()] <= row[a]) 
            result.push(a++); 
        else
        { 
            top_val = row[result.top()]; 
            result.pop(); 
            area = top_val * a; 
            if (!result.empty()) 
                area = top_val * (a - result.top() - 1 ); 
           max_area = max(area, max_area); 
        } 
    } 
    while (!result.empty()) 
    { 
      top_val = row[result.top()]; 
       result.pop(); 
       area = top_val * a; 
       if (!result.empty()) 
            area = top_val * (a - result.top() - 1 ); 
        max_area = max(area, max_area); 
    } 
    return max_area; 
}
int maxRectangle(int A[][MAXCOL])  {
        int result = maxHist(A[0]); 
    for (int a = 1; a < MAXROW; a++) 
    { 
        for (int b = 0; b < MAXCOL; b++) 
            if (A[a][b]) A[a][b] += A[a - 1][b]; 
        result = max(result, maxHist(A[a])); 
    } 
    return result; 
}
 
int main(){
    int matrix[MAXROW][MAXCOL];
    int i,j,x,y
    ;
    cout << "Numero de linhas na matrix: ";
    cin >> i;
    cout << "Numero de colunas na matrix: ";
    cin >> j;
    float l[i][j];
    int p = 0, q = 0;
    while (p < i) {
        while (q < j) {
          cout << "Entre o valor [" << p + 1 << "," << q + 1 << "] da matrix: ";
          cin >> l[p][q];
          q = q + 1;
        }
        p = p + 1;
        q = 0;
    }
    int A[][MAXCOL] = { l[p][q]}; 
    cout << "\nA matrix e:\n ";
    for(x=0;x< i;x++){
         for(y=0;y< j;y++){
            cout << l[x][y]<< " ";
        }
        cout << "\n";   
    }
    cout << "Area of maximum rectangle is "
    << maxRectangle(A); 
 return 0;   
}
        

Answer 1

This line:

int A[][MAXCOL] = { l[p][q]};

declares A and assigns l[p][q] to the first element, and zeroes everything else. You would need a loop to copy l to A . Even better, use std::vector instead of static arrays with maximize sizes.