C++循环试刀

目录

乘方运算

#include <iostream>
using namespace std;
int main()
{
    int resutlt, a, n;
    cin >> a >> n;
    int result = 1;
    for (int i = 0; i < n; i++)
         result *= a;
    cout << result;
    return 0;
}

cin输入的好处

若干整数的最大值

#include <iostream>
using namespace std;
int main()
{
    int n, max;
    cin >> max; //先向max赋予第一个输入值
    while (cin >> n)
    {
         
        if(n > max) max = n;
    }
    cout << max << endl;
    return 0;
}

输入完输入Ctrl + Z / Ctrl + D（结束标志符）
附注 scanf()的值 scanf(“%lf”)
若 3.4 ，值1
若 n, 值0
若EOF, 值-1

斐波那契数列

#include <iostream>
using namespace std;
int main()
{
    int pre ,lat;
    pre = lat = 1;
    int m;
    int k;
    cin >> k;
    for(int i = 0; i < k - 2; i++)
    {
        m = pre + lat;
        pre = lat;
        lat = m;
    }
    cout << lat;
    return 0;
}

求1！+2！+3！+……+n!

繁琐版

#include <iostream>
using namespace std;
int main()
{
    int n;
    int sum = 0, fact;
    int i, k;
    cin >> n;
    for(i = 1; i <= n; i++)
       {
        for(fact = 1, k = 1; k <= i; k++)
            {
                fact *= k;
            }
        sum += fact;
    }
    cout << sum;
    return 0;
}

紧凑版

#include <iostream>
using namespace std;
int main()
{
    int n;
    int sum = 0, fact;
    int i, k;
    cin >> n;
    for(i = 1; i <= n; i++)
       {
        fact *= i;         //注意2！与3！的关系
        sum += fact;
    }
    cout << sum;
    return 0;
}

求不大于n的全部质数(100为例）

#include <iostream>
#include <cstdio>
using namespace std;
int main()
{
    int n;
    int i, k;
    int flag = 1;
    cin >> n;
    int m =2;
    printf("%2d ", m);
    for(i = 3; i <=n; i += 2)        //筛除偶数
    {
        for(k = 3; k < i; k += 2)   //判断i是否为质数
           {
            if(i % k == 0) break;
            if(k * k > i) break;      
           }
        if(k * k > i)
        {
            flag++;
            printf("%2d ", i);
            if(flag % 5 == 0)
            {
                printf("\n");
                flag = 0;
            }
         }
    }
    return 0;
}

输出结果

2 3 5 7 11
13 17 19 23 29
31 37 41 43 47
53 59 61 67 71
73 79 83 89 97

感想：高手的答案总经过进一步改进，更加简洁