计算圆周率

#include<iostream>
#include<ctime>
#include<algorithm>
#include<cstdio>
#include<cmath>
using namespace std;
inline int rd(){
    int x=0,f=1;
    char ch=getchar();
    for(;!isdigit(ch);ch=getchar()) if(ch=='-') f=-1;
    for(;isdigit(ch);ch=getchar()) x=x*10+ch-'0';
    return x*f;
}
int main(){
    srand(time(0));
    system("color 9F");
    unsigned long long cnt1=0,cnt2=0;
    unsigned long long n=rd();
    if(n==0){
        while(1){
            for(int i=1;i<=1000000;i++){
                long double x=(long double)((long double)rand()/(long double)(RAND_MAX));
                long double y=(long double)((long double)rand()/(long double)(RAND_MAX));
                long double z=(long double)(sqrt((long double)(x*x+y*y)));
                if(z<(long double)(1.0)) cnt1++;
                else if(z>(long double)(1.0)) cnt2++;
            }
            long double ans=(((long double)(cnt1+0.0))/((long double)(cnt1+cnt2+0.0))*(long double)(4.0));
            printf("当前π的值为：%.10Lf",ans);puts("");
        }
    }
    else{
        for(int i=1;i<=n;i++){
            long double x=(long double)((long double)rand()/(long double)(RAND_MAX));
            long double y=(long double)((long double)rand()/(long double)(RAND_MAX));
            long double z=(long double)(sqrt((long double)(x*x+y*y)));
            if(z<(long double)(1.0)) cnt1++;
            else if(z>(long double)(1.0)) cnt2++;
        }
        long double ans=(((long double)(cnt1+0.0))/((long double)(cnt1+cnt2+0.0))*(long double)(4.0));
        printf("%.10Lf",ans);
    }
    return 0;
}

 升级版：

#include<iostream>
#include<ctime>
#include<algorithm>
#include<cstdio>
#include<cmath>
using namespace std;
inline int rd(){
    int x=0,f=1;
    char ch=getchar();
    for(;!isdigit(ch);ch=getchar()) if(ch=='-') f=-1;
    for(;isdigit(ch);ch=getchar()) x=x*10+ch-'0';
    return x*f;
}
int main(){
    srand(time(0));
    system("color 9F");
    unsigned long long cnt1=0,cnt2=0;
    unsigned long long n=rd();
    unsigned long long cnt3=0;
    long double s=0;
    if(n==-1){
        while(1){
            cnt3++;
            cnt1=0,cnt2=0;
            for(int i=1;i<=1000000;i++){
                long double x=(long double)((long double)rand()/(long double)(RAND_MAX));
                long double y=(long double)((long double)rand()/(long double)(RAND_MAX));
                long double z=(long double)(sqrt((long double)(x*x+y*y)));
                if(z<=(long double)(1.0)) cnt1++;
                else if(z>(long double)(1.0)) cnt2++;
            }
            long double ans=(((long double)(cnt1+0.0))/((long double)(cnt1+cnt2+0.0))*(long double)(4.0));
            s+=ans;
            printf("\\(^-^)/ 当前π的值为：%.10Lf",s/(long double)(cnt3+0.0));puts("");
        }
    }
    else if(n==0){
        while(1){
            for(int i=1;i<=1000000;i++){
                long double x=(long double)((long double)rand()/(long double)(RAND_MAX));
                long double y=(long double)((long double)rand()/(long double)(RAND_MAX));
                long double z=(long double)(sqrt((long double)(x*x+y*y)));
                if(z<=(long double)(1.0)) cnt1++;
                else if(z>(long double)(1.0)) cnt2++;
            }
            cnt2-=22;
            long double ans=(((long double)(cnt1+0.0))/((long double)(cnt1+cnt2+0.0))*(long double)(4.0));
            printf("\\(^-^)/ 当前π的值为：%.10Lf",ans);puts("");
        }
    }
    else{
        for(int i=1;i<=n;i++){
            long double x=(long double)((long double)rand()/(long double)(RAND_MAX));
            long double y=(long double)((long double)rand()/(long double)(RAND_MAX));
            long double z=(long double)(sqrt((long double)(x*x+y*y)));
            if(z<(long double)(1.0)) cnt1++;
            else if(z>(long double)(1.0)) cnt2++;
        }
        long double ans=(((long double)(cnt1+0.0))/((long double)(cnt1+cnt2+0.0))*(long double)(4.0));
        printf("%.10Lf",ans);
    }
    system("pause"); 
    return 0;
}