inchworm.cpp

using ll = long long;

ll Inchworm(vector<ll> &va, ll k) {
  ll left, right, sum, ans;
  left = right = sum = ans = 0;
  while (left < va.size()) {
    while (right < n && sum + va[right] < k) {
      sum += va[right];
      right++;
    }
 
    ll cnt = va.size() - right;
    ans += cnt;
 
    sum -= va[left];
    if (left == right) {
      right++;
      sum = 0;
    }
    left++;
  }
  
  return ans;
}