100 The 3n + 1 problem

程式碼

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

int ans, cnt;

void f(int x) {
    cnt++;
    if (x == 1) return void(ans = max(ans, cnt));
    if (x & 1) return f(3 * x + 1);
    return f(x / 2);
}

signed main() {
    int a, b;
    while (cin >> a >> b) {
        cout << a << ' ' << b << ' ';
        ans = -1e9;
        if (a > b) swap(a, b);
        for (int i = a; i <= b; i++) {
            cnt = 0;
            f(i);
        }
        cout << ans << endl;
    }
}