PROG-T1080: Tri Again

#include <bits/stdc++.h>
using namespace std;

const int N = 3e4;

int sticks[N + 10];

int main(){

    int nStick;
    scanf("%d", &nStick);
    if(nStick < 3){
        cout << nStick;
        return 0;
    }
    for(int i = 1; i <= nStick; ++i){
        scanf("%d", &sticks[i]);
    }
    sort(sticks + 1, sticks + nStick + 1);

    int lastIdx = lower_bound(sticks + 1, sticks + nStick + 1, sticks[1] + sticks[2]) - sticks;
    int mx = 2;
    for(int i = 1; i <= nStick - 2; ++i){
        while(lastIdx <= nStick && sticks[i] + sticks[i + 1] > sticks[lastIdx]){
            ++lastIdx;
        }
        mx = max(mx, lastIdx - i);
        if(lastIdx > nStick){
            break;
        }
    }
    cout << mx;

    return 0;
}