• Time:O(mn)
• Space:O(n)

## C++

``````class Solution {
public:
int maximalRectangle(vector<vector<char>>& matrix) {
if (matrix.empty())
return 0;

int ans = 0;
vector<int> hist(matrix[0].size());

for (const auto& row : matrix) {
for (int i = 0; i < row.size(); ++i)
hist[i] = row[i] == '0' ? 0 : hist[i] + 1;
ans = max(ans, largestRectangleArea(hist));
}

return ans;
}

private:
int largestRectangleArea(const vector<int>& heights) {
int ans = 0;
stack<int> stack;

for (int i = 0; i <= heights.size(); ++i) {
while (!stack.empty() &&
(i == heights.size() || heights[stack.top()] > heights[i])) {
const int h = heights[stack.top()];
stack.pop();
const int w = stack.empty() ? i : i - stack.top() - 1;
ans = max(ans, h * w);
}
stack.push(i);
}

return ans;
}
};
``````

## JAVA

``````class Solution {
public int maximalRectangle(char[][] matrix) {
if (matrix.length == 0)
return 0;

int ans = 0;
int[] hist = new int[matrix[0].length];

for (char[] row : matrix) {
for (int i = 0; i < row.length; ++i)
hist[i] = row[i] == '0' ? 0 : hist[i] + 1;
ans = Math.max(ans, largestRectangleArea(hist));
}

return ans;
}

private int largestRectangleArea(int[] heights) {
int ans = 0;
Deque<Integer> stack = new ArrayDeque<>();

for (int i = 0; i <= heights.length; ++i) {
while (!stack.isEmpty() && (i == heights.length || heights[stack.peek()] > heights[i])) {
final int h = heights[stack.pop()];
final int w = stack.isEmpty() ? i : i - stack.peek() - 1;
ans = Math.max(ans, h * w);
}
stack.push(i);
}

return ans;
}
}
``````

## Python

``````class Solution:
def maximalRectangle(self, matrix: List[List[str]]) -> int:
if not matrix:
return 0

ans = 0
hist = [0] * len(matrix[0])

def largestRectangleArea(heights: List[int]) -> int:
ans = 0
stack = []

for i in range(len(heights) + 1):
while stack and (i == len(heights) or heights[stack[-1]] > heights[i]):
h = heights[stack.pop()]
w = i - stack[-1] - 1 if stack else i
ans = max(ans, h * w)
stack.append(i)

return ans

for row in matrix:
for i, num in enumerate(row):
hist[i] = 0 if num == '0' else hist[i] + 1
ans = max(ans, largestRectangleArea(hist))

return ans
``````