【Leetcode】85.最大矩形C++（柱状图栈法）

#include "iostream"

#include "vector"

#include "stack"

using namespace std;

class Solution
{
public:
    int maximalRectangle(vector<vector<char>> &matrix)
    {

        int max_y = matrix.size();
        if (max_y == 0)
        {
            return 0;
        }
        int max_x = matrix[0].size();
        int ans = 0, tmp;
        vector<int> dp(max_x, 0);

        for (int i = 0; i < max_y; i++)
        {
            for (int j = 0; j < max_x; j++)
            {
                dp[j] = matrix[i][j] == '1' ? dp[j] + 1 : 0;
            }
            tmp = largestRectangleArea(dp);
            ans = ans > tmp ? ans : tmp;
        }
        return ans;
    }

    int largestRectangleArea(vector<int> &heights)
    {
        stack<int> z;
        z.push(-1);
        int n = heights.size();
        int ans = 0, tmp;
        for (int i = 0; i < n; ++i)
        {
            while (z.top() != -1 && heights[i] < heights[z.top()])
            {
                int tmp = z.top();
                z.pop();
                tmp = heights[tmp] * (i - 1 - z.top());
                ans = ans > tmp ? ans : tmp;
            }
            z.push(i);
        }
        while (z.top() != -1)
        {
            int tmp = z.top();
            z.pop();
            tmp = heights[tmp] * (n - 1 - z.top());
            ans = ans > tmp ? ans : tmp;
        }
        return ans;
    }
};

int main(int argc, char const *argv[])
{
    int y, x;
    cin >> y;
    cin >> x;
    char c;

    vector<vector<char>> matrix(y, vector<char>(x));

    for(int i=0;i<y;i++)
    {
        for(int j=0;j<x;j++)
        {
            cin >> c;
            matrix[i][j] = c;
        }
    }

    Solution so;
    cout << so.maximalRectangle(matrix);

    return 0;
}