Diamond Collector USACO 2016 Silver US Open #2 Help

Debugging Help
#1

Problem Info

Diamond Collector https://usaco.org/index.php?page=viewproblem2&cpid=643

What I’ve Tried

Before reading the official 2-pointers solution, I came up with a solution of O(N*logN), where I check for each index i how many diamonds can fit with it. To prevent overlapping, I used regions so that if i is within the maximum case in the region, it will check if it can replace it and make a new region. I can’t really think of anything wrong with my current solution. If my approach is possibly valid with some fixes, I would appreciate if anyone could check for me.

Code

using namespace std;
using ll = long long;
using pii = pair<int,int>;
#define forr(i,a,b) for (int i = (int)(a); i < (int)(b); ++i)
#define FASTIO ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);

int n,k;
void solve() {
    cin >> n >> k;
    vector<int> v(n);
    forr(i,0,n) {
        cin >> v[i];
    }
    sort(v.begin(),v.end());
    int ans1 = 0, ans2 = 0;
    int startind=0, endind=0, maxinregion = 0;
    bool inregion = false;
    forr(i,0,n) {
        auto it = upper_bound(v.begin(),v.end(),v[i]+k )-1;
        int upper = distance(v.begin(),it); // last index possible 
        if(i<=endind) { // check if in current region
            if(upper-i+1 > maxinregion) {
                maxinregion = upper-i+1;
                startind = i, endind = upper;
                if(maxinregion>ans1) {
                    if(!inregion) ans2 = ans1;
                    ans1 = maxinregion;
                    inregion = true;
                }else if (maxinregion>ans2) {
                    ans2 = maxinregion;
                }
            }
        }else { // new region
            inregion = false;
            maxinregion = upper-i+1;
            endind = upper;
            if(maxinregion>ans1) {
                ans2 = ans1;
                ans1 = maxinregion;
                inregion = true;
            }else if (maxinregion>ans2) {
                ans2 = maxinregion;
            }
        }
    }
    cout << ans1 + ans2;
}

int main() {
    FASTIO;
    solve();
    return 0;
}