前3个wa,最后一个tle，明明样例都对了

P1009 [NOIP1998 普及组] 阶乘之和

zengzeyu @ 2024-04-21 12:24:30

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

string add(string a,string b){
    string baik="",baika="";
    int ai,bi,pla,carry,add_ab,i = 0;
    int alen = a.length();
    int blen = b.length();
    for(int i = 0;i < 200-alen;i++){
        a = "0" + a;   
    }

    for(int i = 0;i < 200-blen;i++){
        b = "0" + b;
    }    

    for(int i = 199;i>=0;i--){
        ai = a[i] - '0';
        bi = b[i] - '0';
        add_ab = ai + bi + carry;
        pla = add_ab % 10;
        /*
        if(pla == 0 && carry == 0){
            break;
        }
        */

        baik = to_string(pla) + baik;
        carry = (add_ab - pla)/10; 
    }
    //cout << a << " + " << b << " = " << baik << endl;
    for(;baik[i] == '0';i++){}
    //cout<<i<<endl;
    for(;i<=199;i++){
        baika = baika + baik[i];
    }
    baik = baika;
    return baik;
}
string mul(string a,string b){
    string mul_ab = "",pro_p = "0";
    int alen = a.length(),blen = b.length(),carry,pla;
    for(int i = blen-1;i >= 0;i--){
        carry = 0;
        mul_ab = "";
        int vb = b[i]-'0';
        for(int j = alen-1;j >= 0;j--){
            int va = a[j]-'0';
            int mab = va * vb + carry;
            pla = mab % 10;

            mul_ab =  to_string(pla)+mul_ab;
            carry = (mab -pla) / 10 ;
            //carry = 0;
        }
        if(carry != 0){
            mul_ab = char(carry + '0')+mul_ab;
        }    
        for(int j = 1;j < blen - i;j++){
            mul_ab = mul_ab + "0";
        }

        pro_p = add(pro_p, mul_ab);

        mul_ab = "";    
    }
    return pro_p;
}

string calcfac(int num){
    string res = to_string(num);
    if(num == 1){
        return res;
    }

    res = mul(res, calcfac(num-1));
    return res;
}

int main(){

    int n = 0;
    string s = "0";
    cin>>n;
    //if(n==6) {
    //  cout << to_string(873) << endl;
    //  return 0;
    //}

    //string fac = "1";

    for(int i = 1; i <= n; i++){
        //fac = mul(fac, to_string(i));
        //cout << i << " "<<fac << " " << s << endl;
        s = add(calcfac(i),s);
    }
    cout<<s;

}

by h120316 @ 2024-04-27 10:34:37

建议缩短代码，求关

by xujihong666 @ 2024-04-27 14:18:52

@zengzeyu 样例对了有不一定是都对

by jasonlixuran @ 2024-05-10 18:20:13

AC代码：

#include<bits/stdc++.h>
using namespace std;
int a[1000010]={0,1},b[1000010]={0,1};//a是累加器，b是阶乘，都从2开始 
int main()
{
    int n;
    cin>>n;
    for(int i = 2; i<=n; i++)
    {
        //先计算阶乘 
        for(int j = 1; j<=100; j++)
        {
            b[j]*=i;
        } 
        for(int j = 1; j<=100; j++)
        {
            b[j+1]+=b[j]/10;
            b[j]%=10;
        }
        //再累加
        for(int j = 1; j<=100; j++)
        {
            a[j]+=b[j];
            a[j+1]+=a[j]/10;
            a[j]%=10;
         } 
    }
    //逆序输出
    int index=100;
    while(a[index]==0)
    {
        index--;
    } 
    for(int i=index; i>=1; i--)
    {
        cout<<a[i]; 
    } 
}

by Tmc2012 @ 2024-05-10 20:28:50

@zengzeyu 代码没那么难，写短一点！

by zengzeyu @ 2024-05-12 11:17:06

@tangmuchen ok

by xujihong666 @ 2024-08-02 15:35:16

#include<bits/stdc++.h>
using namespace std;
int n,a[1000],s[1000],lem=1;
void cheng(int k){
    memset(a,0,sizeof(a));
    a[1]=1;
    for(int i=1;i<=k;i++){
        for(int j=1;j<=lem;j++){
            a[j]*=i;
        }
        for(int j=1;j<=lem;j++){
                a[j+1]+=a[j]/10;
                a[j]%=10;
                if(a[lem+1]!=0)
                lem++;          
        }
    }
}
int main(){
    cin>>n;
    for(int i=1;i<=n;i++){
    cheng(i);
    for(int j=1;j<=lem;j++){
        s[j]+=a[j];
        s[j+1]+=s[j]/10;
        s[j]%=10;
    } 
    }
    while(lem>1){
        if(s[lem]!=0)
        break;
        else
        lem--;
    }
    for(int i=lem;i>=1;i--){
        cout<<s[i];
    } 
    return 0;
}

应该能AC****

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