1919C - Grouping Increases - CodeForces Solution

#include <bits/stdc++.h> 
using namespace std;
typedef long long ll;
 
ll mod = 1e9 + 7;

int returnRes(vector<int> &v) {
	int n = (int)v.size(), res = 0;
	for(int i = 1; i < n; i++) {
		if(v[i] > v[i - 1]) {
			++res;
		}
	}

	return res;
}

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);

	int tt;
	cin >> tt;
	while(tt--) {
		int n;
		cin >> n;
		vector<int> v(n);
		for(int i = 0; i < n; i++) {
			cin >> v[i];
		}

		if(n < 3) {
			cout << "0\n";
			continue;
		}

		vector<int> a, b;
		a.push_back(0);
		a.push_back(v[0]);
		b.push_back(0);

		for(int i = 1; i < n; i++) {
			if(v[i] <= a.back() && v[i] <= b.back()) {
				if(a.back() < b.back()) {
					a.push_back(v[i]);
				} else {
					b.push_back(v[i]);
				}
			} else if(v[i] <= a.back()) {
				a.push_back(v[i]);
			} else if(v[i] <= b.back()) {
				b.push_back(v[i]);
			} else if(a.back() < b.back()) {
				a.push_back(v[i]);
			} else {
				b.push_back(v[i]);
			}
		}

		int res = returnRes(a) + returnRes(b);
		cout << res - 2 + ((int)b.size() == 1 ? 1 : 0) << "\n";
	}
}