84. Largest Rectangle in Histogram（难）

n

​​[2,1,5,6,2,3]​​.

​​10​​

For example,

Given heights = ​​[2,1,5,6,2,3]​​,return ​​10​​.

解释参考​​点击打开链接​​

class Solution {
public:
  int largestRectangleArea(vector<int>& heights) {
    heights.push_back(0);
    int largestArea = 0;
    int i = 0;
    stack<int> stk;
    while (i < heights.size()){
      if (stk.empty() || heights[stk.top()] <= heights[i]){
        stk.push(i);
        i++;
      }
      else{
        int t = stk.top(); stk.pop();
        largestArea = max(largestArea, heights[t] * (stk.empty() ? i : (i - stk.top() - 1)));
      }
    }
    return largestArea;
  }
};