#!/jcode/lang/cpp https://xitu.github.io/jcode-languages/dist/lang-cpp.json

//攒青豆，双指针做法，By铁皮果冻
#include<iostream>
#include<vector>
using namespace std;
int main(){
    vector<int> height {5,0,2,1,4,0,1,0,3};
    int left=0,leftMax=height[0],right=height.size()-1,rightMax=height[right];
    int sum = 0;
    while(left<right){
        if(height[left]>leftMax){
            leftMax = height[left];
        }
        if(height[right]>rightMax){
            rightMax = height[right];
        }
        if(height[left]<height[right]){
            sum+=leftMax-height[left];
            left++;
        }else{
            sum+=rightMax-height[right];
            right--;
        }
    }
    cout<<"Answer is = "<<sum<<endl;
    return 0;
}