leetcode[84]Largest Rectangle in Histogram

Given n non-negative integers representing the histogram's bar height where the width of each bar is 1, find the area of largest rectangle in the histogram.



Above is a histogram where width of each bar is 1, given height =

[2,1,5,6,2,3]

.



The largest rectangle is shown in the shaded area, which has area =

10

unit.

For example,
Given height =

[2,1,5,6,2,3]

,
return

10

.

class Solution {
public:
/*
int Max(int a, int b){return a > b ? a : b;}
int largestRectangleArea(vector<int> &height) {
height.push_back(0);
stack<int> stk;
int i = 0;
int maxArea = 0;
while(i < height.size()){
if(stk.empty() || height[stk.top()] <= height[i]){
stk.push(i++);
}else {
int t = stk.top();
stk.pop();
maxArea = Max(maxArea, height[t] * (stk.empty() ? i : i - t));
}
}
return maxArea;
}

int largestRectangleArea(vector<int> &height)
{
if(height.empty())return 0;
height.push_back(0);
int maxRes=0;
stack<int> sta;
for (int i=0;i<height.size();i++)
{
if (sta.empty()||(!sta.empty()&&height[i]>=height[sta.top()]))
{
sta.push(i);
}
else
{
int top;
int newRes;
while(!sta.empty()&&height[i]<height[sta.top()])
{
top=sta.top();
sta.pop();
newRes=(sta.empty()?i:(i-sta.top()-1))*height[top];
maxRes=maxRes>newRes?maxRes:newRes;

}
sta.push(i);
}
}
return maxRes;
}
*/
int largestRectangleArea(vector<int> &height)
{
if(height.empty())return 0;
height.push_back(0);
int maxRes=0;
stack<int> sta;
for (int i=0;i<height.size();i++)
{
int top;
int newRes;
while(!sta.empty()&&height[i]<height[sta.top()])
{
top=sta.top();
sta.pop();
newRes=(sta.empty()?i:(i-sta.top()-1))*height[top];
maxRes=maxRes>newRes?maxRes:newRes;
}
sta.push(i);
}
return maxRes;
}
};