C语言算法小程序

99乘法表

#include <stdio.h>
int main()
{
    for (int i = 1; i < 10; i++)
    {
        for (int j = 1; j < 10; j++)
        {
            if (j > i)
                break;
            else
            {
                printf("%d × %d = %-2d  ", i, j, i * j);
            }
        }
        printf("\n");
    }
}

求指定底数幂

#include <stdio.h>
int main()
{
    float x, y, res = 1, i = 0;
    printf("请输入底数：");
    scanf("%f", &x);
    printf("请输入幂(正数)：");
    scanf("%f", &y);
    if (y < 0)
    {
        printf("请输入正数"); /* code */
    }
    else
    {

        while (i < y)
        {
            res *= x; /* code */
            i++;
        }
        printf("res=%f\n", res); /* code */
    }
}

数字打印机

#include <stdio.h>
int main()
{
    int x, y;
    printf("请输入想要循环的数字（整数）:");
    scanf("%d", &y);
    printf("请输入循环次数（注意不得超过一百，且为正整数）：");
    scanf("%d", &x);
    if (x > 100 || x < 1)
    {
        printf("您输入的数不符合规矩"); /* code */
    }
    else
    {
        printf("即将开始循环%d次\n", x);
        for (int i = 0; i < x; i++)
        {
            printf("%d\n", y);
        }
    }
}

摇骰子中奖

#include <stdio.h>
void main()
{
    int a;
    printf("请在1-6之间输入一个数\n");
    scanf("%d", &a);
    if (a > 6 || a < 1)
    {
        printf("您输入的数不在范围");
    }
    else
    {
        switch (a)
        {
        case 6:
            printf("恭喜中将");
            break;
        case 4:
            printf("恭喜中奖");
            break;
        case 2:
            printf("恭喜中奖");
        default:
            printf("很遗憾，未中奖");
            break;
        }
    }
}

自动寻找水仙花数

#include <stdio.h>
int main()
{
    for (int i = 100; i < 1000; i++)
    {
        int b = i / 100, /* code */
            s = i / 10 % 10,
            g = i % 10;
        if (b * b * b + s * s * s + g * g * g == i)
        {
            printf("%d是水仙花数！\n", i); /* code */
        }
    }
}

0-9从大到小排序

基础版

#include <stdio.h>
int main()
{
    int arr[10] = {3, 5, 7, 2, 9, 0, 6, 1, 8, 4}, a;
    for (int x = 0; x < 10; x++)
    {
        for (int i = 1; i < 10; i++)
        {
            if (arr[i] > arr[i - 1])
            {
                a = arr[i];
                arr[i] = arr[i - 1];
                arr[i - 1] = a;
            }
        }
    }
    for (int i = 0; i < 10; i++)
    {
        printf("%d  ", arr[i]);
    }
}

优化版

#include <stdio.h>
int main()
{
    int arr[10] = {3, 5, 7, 2, 9, 0, 6, 1, 8, 4}, a;
    for (int x = 10; x > 0; x = x - 1)
    {
        for (int i = 1; i < 10; i++)
        {
            if (arr[i - 1] > arr[i])
            {
                a = arr[i - 1];
                arr[i - 1] = arr[i];
                arr[i] = a;
            }
        }
    }
    for (int i = 0; i < 10; i++)
    {
        printf("%d  ", arr[i]);
    }
}

高级优化

#include <stdio.h>
int main()
{
    int arr[10] = {3, 5, 7, 2, 9, 0, 6, 1, 8, 4}, a;
    for (int x = 0; x < 10; x++)
    {
        _Bool flag = 0;
        for (int i = 1; i < 10 - x; i++)
        {
            if (arr[i - 1] > arr[i])
            {
                a = arr[i];
                arr[i] = arr[i - 1];
                arr[i - 1] = a;
                flag = 1;
            }
        }
        if (flag == 0)
            break;
    }
    for (int i = 0; i < 10; i++)
    {
        printf("%d  ", arr[i]);
    }
}

打劫穷舍算法

#include <stdio.h>
int main()
{
    int value[] = {254, 545, 654, 578, 845, 754, 854, 954}, size = 8, dp[size], result; /*dp[size]要在size后*/
    //*前面两个都已经知道了所以直接写出来
    dp[0] = value[0];
    dp[1] = value[1];
    for (int i = 2; i < size; i++)
        dp[i] = dp[i - 1] > dp[i - 2] + value[i] ? dp[i - 1] : dp[i - 2] + value[i]; /*递推公式*/
    result = dp[size - 1];

    printf("%d是最大钱数",result);
}

回文串

#include <stdio.h>
#include <string.h>
int main()
{
    char str[64];
    gets(str);
    int len = strlen(str), left = 0, right = len - 1;

    _Bool flag = 1;

    while (left<right)
    {
        if (str[left]!=str[right])
        {    flag = 0;
        break;
        }
        left++;
        right--; /* code */
    }

    puts(flag ? "是回文串" : "不是回文串");
}

求斐波那契数列指定位数

#include <stdio.h>
int main()
{
    long long target, a = 1, b = 0, c = 0;
    printf("请输入想要获取的斐波那契位数(不超过153)：");
    scanf("%d", &target);
    if (target == 1)
    {
        printf("1");
    }
    else
    {
        for (int i = 0; i < target - 1; i++)
        {
            c = b;
            b = a;
            a = a + c;
        }
        printf("%lld", a);
    }
}

数组优化版

#include <stdio.h>
int main()
{
    long long fib[a],a,fb;
    printf("请输入想要获取的斐波那契位数(不超过153)：");
    scanf("%d", &a);
    fib[1] = fib[0] = 1;
    for (long long i = 2; i < a; i++)
    {
        fib[i] = fib[i - 1] + fib[i - 2];
        fb = fib[i-1]; /* code */
    }
    printf("%lld",fb);
}