hackerearth yesterday contest

general
1

guys here is the question which was asked yesterday on hackerearth : question

actually they haven’t released the editorial yet so can you help me with this . I am getting wrong answer .

here is the code :

        #include <bits/stdc++.h>
         
        using namespace std;
         
        # define MOD 1000000009
        # define pi 3.141593
         
        template<class T> inline void read(T& x) {
            char ch;
            while(!isdigit(ch = getchar_unlocked()));
            x = ch-'0';
            while( isdigit(ch = getchar_unlocked())) x *= 10, x += ch-'0';
        }
         
        int main(){
            long n;
            cin >> n;
            long a[n+2];
            vector < pair <long,long> > b;
            for(long i = 0 ; i < n ; i++){
                cin >> a[i];
                if(i != 0 && i != n-1){
                    b.push_back(make_pair(a[i],i));
                }
            }
            sort(b.begin(),b.end());
            long long answer = 0;
            long index,left,right,left_index,right_index;
            for(long i = 0 ; i < b.size() ; i++){
                index = b[i].second;
                a[index] = 0;
                left_index = index-1;
                right_index = index+1;
                while(a[left_index] == 0){
                    left_index--;
                }
                while(a[right_index] == 0){
                    right_index++;
                }
                answer = answer + min(a[left_index],a[right_index]);
            }
            cout << answer;
            return 0;
        }