求助：关于全局变量归零的问题！！
#include <iostream>using namespace std;int a=0;void f(int n){ a+=n; if (n!=1) f(n-1);}int main(){ int n; while (cin >> n) cout << a << endl; return 0;}#include <iostream>using namespace std;int a=0;void f(int n){ a+=n; if (n!=1) f(n-1);}int main(){ int n; while (cin >> n){ a=0; f(n); cout << a << endl; } return 0;}