Mobiles

#include <bits/stdc++.h>
using namespace std;
int t[100001][2], r[100001][2];
int b=0, d=0, y=0;
void f(int a, int c){
	if (a==-1) {
		if (b==0) {
			b=c;
			d=1;
		}
		else if (c==b+1){
			if (d!=2 && d!=1) d=4;
			else d=2;
		}
		else if (c==b-1){
			if (d!=1 && d!=3) d=4;
			else d=3;
		}
		else if (c!=b) d=4;
	}
	else {
		f(t[a][0], c+1);
		f(t[a][1], c+1);
	}
}
int g(int a){
	if (a==-1) return 1;
	else {
		r[a][0]=g(t[a][0]);
		r[a][1]=g(t[a][1]);
		if (r[a][0]<r[a][1]) y++;
		return r[a][0]+r[a][1];
	}
}
int main(){
	int a, b, n, x=0;
	cin >> n;
	for (int i=1; i<=n; ++i) {
		cin >> a >> b;
		t[i][0]=a;
		t[i][1]=b;
		if ((a==-1 && b!=-1) || (a!=-1 && b==-1) ) x++;
	}
	f(1, 1);
	if (d==4 || x>1) cout << "-1";
	else if (d==1) cout << "0\n";
	else{
		g(1);
		cout << y << "\n";
	}
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

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: WRONG ANSWER

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: ACCEPTED

Test 28

Verdict: ACCEPTED

Test 29

Verdict: ACCEPTED

Test 30

Verdict: ACCEPTED

Test 31

Verdict: ACCEPTED

Test 32

Verdict: ACCEPTED

Test 33

Verdict: ACCEPTED

Test 34

Verdict: ACCEPTED

Test 35

Verdict: ACCEPTED

Test 36

Verdict: ACCEPTED

Test 37

Verdict: ACCEPTED

Test 38

Verdict: ACCEPTED

Test 39

Verdict: ACCEPTED

Test 40

Verdict: ACCEPTED

Test 41

Verdict: ACCEPTED

Test 42

Verdict: ACCEPTED