In the following code,

#include <iostream>
#include <vector>
using namespace std;

vector <int> otm;
vector <int> past;
vector <int> strength;

bool leaves(int n){
    for (int i = 0; i < n; i++){
        if (otm[i] == 1 && past[i] == 0 && strength[i] < strength[0]){
            return true;
        }
    }
    return false;
}

int main()
{
    int n;
    cin >> n;
    otm.resize(n, 1);
    
    for (int i = 0; i < n; i++){
        int a;
        cin >> a;
        strength.push_back(a);
    }
    
    int prep[n];
    past.resize(n, 0);
    
    for (int i = 0; i < n - 1; i ++){
        int a;
        int b;
        cin >> a >> b;
        prep[b - 1] = a - 1;
        past[a - 1]++;

    }
    
    while (leaves(n)){
        for (int i = 0; i < n; i++){
            if (otm[i] == 1 && past[i] == 0 && strength[i] < strength[0]){ //this is 48 line
                otm[i] = 0;
                past[prep[i]]--;
            }
        }
    }
    
    int sum = 0;
    for (int i = 0; i < n; i++){
        if (otm[i] == 1){
            sum++;
        }
    }
    cout << sum - 1;
}

changing line 48 to:
if (otm[i] == 1 && past[i] == 0 && strength[i] > strength[0]){
like its supposed to be, it goes into an infinite loop. Any ideas as to why it leads to an infinite loop?