class Solution { public: int trap(vector<int>& height) { int left=0; int right=height.size()⑴; int leftmax=0; //左側(cè)最大值 int rightmax=0; //右側(cè)最大值 int res=0; //結(jié)果 while(left<=right) { if(height[left]<=height[right]) { if(height[left]>leftmax) leftmax=height[left]; else res+=leftmax-height[left]; left++; } else { if(height[right]>rightmax) rightmax=height[right]; else res+=rightmax-height[right]; right--; } } return res; } };