Mobiles

input/code.cpp: In function 'void haku2(int)':
input/code.cpp:31:7: warning: variable 'ok' set but not used [-Wunused-but-set-variable]
  bool ok = false;
       ^~

#include <bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define ld long double
#define N (1<<18)
#define M 1000000007
#define P complex<long long>
#define X real()
#define Y imag()

using namespace std;

int n, a, b, par[201010], lvl[201010], cnt=2, rs[101010], l[202020], r[202020], lit[202020], rit[202020], ans;
vector<int> laps[201010], v, v2; // laps
vector<int> taso[202020];

void haku(int s) {
	if(l[s]) {
		lvl[l[s]] = lvl[s]+1;
		haku(l[s]);
	}
	if(r[s]) {
		lvl[r[s]] = lvl[s]+1;
		haku(r[s]);
	}
	v.push_back(s);
	taso[lvl[s]].push_back(s);
}

void haku2(int s) {
	bool ok = false;
	if(l[s]) {
		haku2(l[s]);
	} else {
		v2.push_back(lvl[s]);
		ok = true;
	}
	if(r[s]) {
		haku2(r[s]);
	} else {
	}
}
int main() {
	cin.tie(0);
	cout.tie(0);
	ios_base::sync_with_stdio(0);
	cin >> n;
	rs[1] = 1;
	for(int i=1; i<=n; i++) {
		cin >> a >> b;
		int aS = cnt;
		if(a != -1)
			rs[a] = aS;
		cnt++;
		int bS = cnt;
		if(b != -1)
			rs[b] = bS;
		cnt++;
		l[rs[i]] = aS;
		r[rs[i]] = bS;
		laps[rs[i]].push_back(aS);
		laps[rs[i]].push_back(bS);
	}
	haku(1);
	for(int i=200020; i>=0; i--) {
		for(auto u:taso[i]) {
			if(l[u]) {
				lvl[u] = max(lvl[u], lvl[l[u]]);
			}
			if(r[u]) {
				lvl[u] = max(lvl[u], lvl[r[u]]);
			}
		}
	}
	for(int i=200020; i>=0; i--) {
		for(auto u:taso[i]) {
			if(l[u]) {
				lvl[u] = min(lvl[u], lvl[l[u]]);
			}
			if(r[u]) {
				lvl[u] = min(lvl[u], lvl[r[u]]);
			}
			if(l[u] && r[u]) {
				if(lvl[l[u]] < lvl[r[u]]) {
					ans++;
					swap(r[u], l[u]);
				}
			}
		}
	}
	haku2(1);
	bool ok = false;
	int ed = v2[0];
	for(auto u:v2) {
		if(u != ed) {
			if(ed-u != 1) {
				cout << -1;
				exit(0);
			} else {
				if(ok) {
					cout << -1;
					exit(0);
				} else {
					ok = true;
				}
			}
		}
		ed = u;
	}
	cout << ans << endl;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: WRONG ANSWER

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: WRONG ANSWER

Test 28

Verdict: ACCEPTED

Test 29

Verdict: ACCEPTED

Test 30

Verdict: WRONG ANSWER

Test 31

Verdict: WRONG ANSWER

Test 32

Verdict: ACCEPTED

Test 33

Verdict: WRONG ANSWER

Test 34

Verdict: ACCEPTED

Test 35

Verdict: WRONG ANSWER

Test 36

Verdict: WRONG ANSWER

Test 37

Verdict: ACCEPTED

Test 38

Verdict: ACCEPTED

Test 39

Verdict: WRONG ANSWER

Test 40

Verdict: WRONG ANSWER

Test 41

Verdict: WRONG ANSWER

Test 42

Verdict: WRONG ANSWER