Binary tree

input/code.cpp: In function 'long long int sign(long long int)':
input/code.cpp:13:82: warning: control reaches end of non-void function [-Wreturn-type]
 int sign(int a){if(a < 0){ return -1;}if(a == 0) {return 0;}if(a > 0) {return 1;}}
                                                                                  ^

#include <bits/stdc++.h>
using namespace std;

#define int long long
#define INF 9223372036854775807
#define M_PI 3.14159265358979323846
#define double long double

int mod = 1000000007;

int fastPow(int b, int e){int r = 1;while(e){if(e%2 == 1){r*=b;r%=mod;}b*=b;b%=mod;e/=2;}return r;}
int pgcd(int a, int b){ if(a%b == 0) return b; else return pgcd(b, a%b);}
int sign(int a){if(a < 0){ return -1;}if(a == 0) {return 0;}if(a > 0) {return 1;}}
bool isPrime(int a){if(a == 1) {return false;}int f = sqrt(a);for(int i = 2; i<=f; i++){if(a%i == 0){return false;}}return true;}
int toInt(string s){int tot = 0;for(int i = s.size()-1; i >= 0; i--){tot+=((s[i]-'0')%mod)*fastPow(10,i);tot%=mod;}return tot;}
string toString(int a){string s = "";while(a){s = (char)('0'+a%10) + s;a/=10;}return s;}

signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n, m;
    cin >> n >> m;
    vector<int> v(m);
    for(int i = 0; i < m; i++){
        cin >> v[i];
    }
    sort(v.begin(), v.end());
    int left = fastPow(2,n-2);
    int right = left;
    set<int> visited;
    for(int a : v){
        if(a == 1 || a == 2 || a == 3){
            left = 0;
            break;
        }
        int t = a;
        int sz = 0;
        bool v = false;
        while(a > 3){
            if(visited.count(a)){
                v = true;
                break;
            }
            a/=2;
            sz++;
        }
        if(v) continue;
        visited.insert(t);
        if(a == 2){
            left-=fastPow(2,n-2-sz);
            left+=mod;
            left%=mod;
        }else if(a == 3){
            right-=fastPow(2,n-2-sz);
            right+=mod;
            right%=mod;
        }else{
            assert(0);
        }
    }
    cout << (((left*right)%mod)*2)%mod << endl;
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: ACCEPTED

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 1

Verdict: ACCEPTED

Test 7

Group: 1

Verdict: ACCEPTED

Test 8

Group: 1

Verdict: ACCEPTED

Test 9

Group: 1

Verdict: ACCEPTED

Test 10

Group: 1

Verdict: ACCEPTED

Test 11

Group: 1

Verdict: ACCEPTED

Test 12

Group: 1

Verdict: ACCEPTED

Test 13

Group: 1

Verdict: ACCEPTED

Test 14

Group: 1

Verdict: ACCEPTED

Test 15

Group: 1

Verdict: ACCEPTED

Test 16

Group: 1

Verdict: ACCEPTED

Test 17

Group: 1

Verdict: ACCEPTED

Test 18

Group: 1

Verdict: ACCEPTED

Test 19

Group: 1

Verdict: ACCEPTED

Test 20

Group: 1

Verdict: ACCEPTED

Test 21

Group: 1

Verdict: ACCEPTED

Test 22

Group: 1

Verdict: ACCEPTED

Test 23

Group: 1

Verdict: ACCEPTED

Test 24

Group: 1

Verdict: ACCEPTED

Test 25

Group: 1

Verdict: ACCEPTED

Test 26

Group: 1

Verdict: ACCEPTED

Test 27

Group: 1

Verdict: ACCEPTED

Test 28

Group: 1

Verdict: ACCEPTED

Test 29

Group: 1

Verdict: ACCEPTED

Test 30

Group: 1

Verdict: ACCEPTED

Test 31

Group: 1

Verdict: ACCEPTED

Test 32

Group: 1

Verdict: ACCEPTED

Test 33

Group: 1

Verdict: ACCEPTED

Test 34

Group: 1

Verdict: ACCEPTED

Test 35

Group: 1

Verdict: ACCEPTED

Test 36

Group: 2

Verdict: ACCEPTED

Test 37

Group: 2

Verdict: ACCEPTED

Test 38

Group: 2

Verdict: ACCEPTED

Test 39

Group: 2

Verdict: ACCEPTED

Test 40

Group: 2

Verdict: ACCEPTED

Test 41

Group: 2

Verdict: ACCEPTED

Test 42

Group: 2

Verdict: ACCEPTED

Test 43

Group: 2

Verdict: ACCEPTED

Test 44

Group: 2

Verdict: ACCEPTED

Test 45

Group: 2

Verdict: ACCEPTED

Test 46

Group: 3

Verdict: ACCEPTED

Test 47

Group: 3

Verdict: ACCEPTED

Test 48

Group: 3

Verdict: ACCEPTED

Test 49

Group: 3

Verdict: ACCEPTED

Test 50

Group: 3

Verdict: ACCEPTED

Test 51

Group: 3

Verdict: ACCEPTED

Test 52

Group: 3

Verdict: ACCEPTED

Test 53

Group: 3

Verdict: ACCEPTED

Test 54

Group: 3

Verdict: ACCEPTED

Test 55

Group: 3

Verdict: ACCEPTED

Test 56

Group: 3

Verdict: ACCEPTED

Test 57

Group: 3

Verdict: ACCEPTED

Test 58

Group: 3

Verdict: ACCEPTED

Test 59

Group: 3

Verdict: ACCEPTED

Test 60

Group: 3

Verdict: ACCEPTED

Test 61

Group: 3

Verdict: ACCEPTED

Test 62

Group: 3

Verdict: ACCEPTED

Test 63

Group: 3

Verdict: ACCEPTED

Test 64

Group: 3

Verdict: ACCEPTED

Test 65

Group: 3

Verdict: ACCEPTED

Test 66

Group: 3

Verdict: ACCEPTED

Test 67

Group: 3

Verdict: ACCEPTED

Test 68

Group: 3

Verdict: ACCEPTED

Test 69

Group: 3

Verdict: ACCEPTED

Test 70

Group: 3

Verdict: ACCEPTED

Test 71

Group: 3

Verdict: ACCEPTED

Test 72

Group: 3

Verdict: ACCEPTED

Test 73

Group: 3

Verdict: ACCEPTED

Test 74

Group: 3

Verdict: ACCEPTED

Test 75

Group: 3

Verdict: ACCEPTED

Test 76

Group: 3

Verdict: ACCEPTED

Test 77

Group: 3

Verdict: ACCEPTED