出现了不明原因的3221225477返回值

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

int n;
vector<int> ans;

vector<int> add(vector<int> a,vector<int> b){
    vector<int> res;
    res.resize(114514);
    int x = 0;
    for(int i = 0;i < max(a.size(),b.size());i++){
        res[i] = a[i] + b[i] + x;
        x = res[i] / 10;
        res[i] %= 10;
    }
    return res;
}
vector<int> cf(vector<int> a,int b){
    vector<int> res;
    res.resize(114514);
    int x = 0;
    for(int i = 0;i < a.size();i++){
        res[i] = a[i] * b + x;
        x = res[i] / 10;
        res[i] %= 10;
    }
    return res;
}
vector<int> fact(int x){
    vector<int> res;
    res[0] = 1;
    for(int i = 1;i <= x;i++){
        res = cf(res,i);
    }
    return res;
}

int main(){
    cin>>n;
    for(int i = 1;i <= n;i++){
        ans = add(ans,fact(i));
    }
    bool flag = false;
    for(int i = ans.size() - 1;i >= 0;i--){
        if(ans[i] == 0 && !flag) continue;
        else{
            cout<<ans[i];
            flag = true;
        }
    }
    return 0;
}

编译器：TDM-GCC 4.9.2 64-bit Debug