练兵区：

1、二分法求根

#include <stdio.h>
#include <math.h>

void GetValue(float* value, float left, float right);

int main()
{
    float left;//左区间
    float right;//右区间
    float mid;

    scanf("%f,%f", &left, &right);
    GetValue(&mid, left, right);
    printf("x=%6.2f\n", mid);
    return 0;
}

void GetValue(float* value, float left, float right)
{
    float temp;
    do
    {
        *value = (left + right) / 2;
        temp = pow(*value, 3) - *value - 1;
        if (temp < 0)
        {
            left = *value;
        }
        else
            right = *value;

    } while (fabs(temp) > 1e-6);
}

2、 矩阵转置

#include <stdio.h>

#define N 5

void GetArray(int a[][N], int n);

int main()
{
    int n;
    int array[10][5] = {0};
    scanf("%d", &n);
    GetArray(array, n);
    printf("The original matrix is:\n");
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < n; j++)
        {
            printf("%3d", array[i][j]);
        }
        printf("\n");
    }
    printf("The changed matrix is:\n");
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < n; j++)
        {
            printf("%3d", array[i+5][j]);
        }
        printf("\n");
    }
}

void GetArray(int a[][N],int n)
{
    int i, j;
    int temp;
    for (i = 0; i < n; i++)
        for (j = 0; j<n; j++)
        {
            a[i][j] = i * n + j + 1;
            a[j + 5][i] = a[i][j];
        }

}

3、程序改错

#include  <stdio.h>
#define ARR_SIZE 10

void MaxMinExchang(int *a, int n);

int main()
{
    int a[ARR_SIZE], i, n;
    printf("Input n(n<=10):\n");
    scanf("%d", &n);
    printf("Input %d Numbers:\n", n);
    for (i = 0; i < n; i++)
    {
        scanf("%d", &a[i]);
    }
    MaxMinExchang(a, n);
    printf("After MaxMinExchange:\n");
    for (i = 0; i < n; i++)
    {
        printf("%d ", a[i]);
    }
    printf("\n");
    return 0;
}
void  MaxMinExchang(int *a, int n)
{
    int  maxValue = a[0], minValue = a[0], maxPos ,minPos ;
    int  i, temp;
    maxPos = minPos = 0;
    for (i = 0; i < n; i++)
    {
        if (a[i] > maxValue)
        {
            maxValue = a[i];
            maxPos = i;
        }
        if (a[i] < minValue)
        {
            minValue = a[i];
            minPos = i;
        }
    }
    temp = a[maxPos];
    a[maxPos] = a[minPos];
    a[minPos] = temp;
}

4蛇形矩阵

这一题你会发现行列之后为偶数，走向为右上；行列之后为奇数，走向为左下；然后碰到边界会变直线，于是考虑一下边界情况题目就很简单了。

# include <stdio.h>

#define N 100

void ZigzagMatrix(int a[][N], int n);

int main()
{
    int n;
    int a[N][N] = { 0 };
    printf("Input n:\n");
    if (scanf("%d", &n) != 1)
        printf("Input error!\n");
    else
    {
        if (n<=0 || n>=100)
            printf("Input error!\n");
        else
        {
            ZigzagMatrix(a, n);
            for (int i = 0; i < n; i++)
            {
                for (int j = 0; j < n; j++)
                    printf("%4d", a[i][j]);
                printf("\n");
            }
        }
    }
        

    return 0;
}

void ZigzagMatrix(int a[][N], int n)
{
    int counter = 1;
    int i = 0, j = 0;
    while (1)
    {
        a[i][j] = counter;
        counter++;
        //i+j都为偶数，移动方向为右上，遇到边界有一个条件不变化
        if ((i+j)%2 == 0)
        {
            if (i == n - 1 && j == n - 1)
                break;
            else if (i == 0 && j != n - 1)
            {
                j++;
            }
            else if (j == n - 1)
                i++;
            else
            {
                i--; j++;
            }
        }
        //i+j为奇数，移动方向为左下，同样受限于边界
        else
        {
            if (j == 0 && i != n - 1)
                i++;
            else if (i == n - 1)
                j++;
            else
            {
                i++; j--;
            }
        }
    }
}

5 亲密数_1

···

include <stdio.h>

include <assert.h>

void GetDivisors(int *tempa, int a);

int main()
{
int a, b;
int tempa, tempb;
printf("Input m, n:\n");
if (scanf("%d,%d", &a, &b) != 2)
assert(1);
else
{
GetDivisors(&tempa, a);
GetDivisors(&tempb, b);
if (tempa == b && tempb == a)
printf("Yes!\n");
else
printf("No!\n");
}

return 0;

}

void GetDivisors(int* tempa, int a)
{
int small, large;
int i, j;
*tempa = 1;
for (small = 2, large = a; small < large; small++)
{
if (a % small == 0)
{
large = a / small;
*tempa += small + large;
}
}
if (a / small == small)
*tempa += small;

}
···

6 亲密数_2

# include <stdio.h>
#include <assert.h>

void GetDivisors(int *tempa, int a);

int main()
{
    int n;
    int i, j, tempi ,tempj;
    int a[100];
    int count = 0;
    printf("Input n:\n");
    scanf("%d", &n);
    for (i = 2; i <= n; i++)
    {
        GetDivisors(&tempi, i);
        GetDivisors(&tempj, tempi);
        if (tempj == i && tempi != i)
        {
            for (j = 0; j < count; j++)
                if (a[j] == i)
                    goto A;
            a[count] = i;
            a[count + 1] = tempi;
            printf("(%d,%d)\n", a[count], a[count + 1]);
            count += 2;

        A:;
        }
    }

    return 0;
}

void GetDivisors(int* tempa, int a)
{
    int small, large;
    int i, j;
    *tempa = 1;
    for (small = 2, large = a; small < large; small++)
    {
        if (a % small == 0)
        {
            large = a / small;
            *tempa += small + large;
        }
    }
    if (a / small == small)
        *tempa += small;

}

7 完全数

···

include <stdio.h>

include <assert.h>

int GetDivisors(int m, int a[]);

int main()
{
int m;
int i, j;
int a[100];
int count;
printf("Input m:\n");
scanf("%d", &m);
if (count = GetDivisors(m, a))
{
printf("Yes!\n");
for (i = 0; i < count; i++)
{
if (i == count-1)
printf("%d", a[i]);
else
printf("%d,", a[i]);

    }
        
}
else
    printf("No!\n");

return 0;

}

int GetDivisors(int m, int a[])
{
int i, j;
int count = 0, sum = 0;
for (i=1; i<m; i++)
{
if (m % i == 0)
{
a[count] = i;
count++;
sum += i;
}
}
if (m == sum)
return count;
else
return 0;
}
···

8 回文素数

···

include <stdio.h>

include <math.h>

int IsPrime(int n);
int IsPalindromic(int n);

int main()
{
int n;
int i;
int count = 0;
printf("Input n:\n");
scanf("%d", &n);
for (i = 10; i <= n; i++)
{
if (IsPrime(i) && IsPalindromic(i))
{
printf("%4d", i);
count++;
}

}
printf("\ncount=%d\n", count);

return 0;

}

int IsPalindromic(int n)
{
if (n/100==n%10 || n / 10 == n % 10)
return 1;
else
return 0;
}

int IsPrime(int n)
{
int i;
for (i = 2; i <= sqrt(n); i++)
{
if (n % i == 0)
return 0;
}
return 1;
}
···

9 梅森尼数

···

include <stdio.h>

include <math.h>

int IsPrime(double n);

int main()
{
int n;
int i, count=0;
double temp=1;
printf("Input n:\n");
scanf("%d", &n);
for (i = 1; i < n; i++)
{
temp *= 2;
if (IsPrime(temp - 1))
{
printf("2^%d-1=%.0lf\n", i, temp - 1);
count++;
}
}
printf("count=%d\n", count);
return 0;
}

int IsPrime(double n)
{
double i;
if (n == 1)
return 0;
for (i = 2; i <= sqrt(n); i++)
{
if (n / i == (int)(n/i))
return 0;
}
return 1;
}
···

10工资统计

···

include<stdio.h>

void Input(float wage[], int n);

float Compute(float wage[], int n, float* pmaxwage, float* pminwage);

int main()

{

float wage[50], maxwage, minwage, avewage;

int n;



printf("Please input n:\n");

scanf("%d", &n);



Input(wage, n);

avewage = Compute(wage, n, &maxwage, &minwage);



printf("maxwage=%.2f, minwage=%.2f, avewage=%.2f\n", maxwage, minwage, avewage);



return 0;

}

void Input(float wage[], int n)

{
for (int i = 0; i < n; i++)
{
scanf("%f", &wage[i]);
}
}

float Compute(float wage[], int n, float* pmaxwage, float* pminwage)

{
float averwage=0;
int i;
*pmaxwage = *pminwage = wage[0];
for (i = 0; i < n; i++)
{
if (wage[i] > * pmaxwage)
*pmaxwage = wage[i];
if (wage[i] < *pminwage)
*pminwage = wage[i];
averwage += wage[i] / n;
}
return averwage;

}
···