LeetCode Solutions
84. Largest Rectangle in Histogram
Time: $O(n)$ Space: $O(n)$
class Solution {
public:
int largestRectangleArea(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;
}
};
class Solution {
public 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;
}
}
class Solution:
def largestRectangleArea(self, 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