C语言经典算法实例-优快云博客

本文链接：https://blog.youkuaiyun.com/QQhelphelp/article/details/87907935

#include<stdio.h>
int prime(int m);
int isPerfect(int n,int a[]);
void selectSort(int a[],int n);
void bubbleSort(int a[],int n);
int search(int a[],int n,int x);
void converse(int n,int k,char st[]);
void fun(int *p,int n,int m);
main(){
/*1.输入两个整数存放于变量中，实现两变量值交换 */
int num1,num2,temp;
printf("Please input two Integers:");
scanf("%d %d",&num1,&num2);
temp=num1;
num1=num2;
num2=temp;
printf("After exchange,num1=%d,num2=%d",num1,num2);
/*2.求和，从键盘输入正整数n,求1+2+3+。。。+*/
int n,sum,i;
printf("Please inout n（>0）");
scanf("%d",&n);
sum=0;
for(i=1;i<=n;i++){
sum+=i;
}
printf("1+2+3+...+%d=%d",n,sum);
/*3.求阶乘*/
int n,i;
long fac;
printf("Please input n(>0)");
scanf("%d",&n);
fac=1;
for(i=1;i<=n;i++){
fac*=i;
}
printf("1*2*3*...*%d=%ld",n,fac);
/*4.用随机函数产生100个【0，99】内的随机整数，要求每行5个打印，并统计小于60，60-85，大于85个数并打印结果*/
int a[100],i,count1,count2,count3;
count1=count2=count3=0;
for(i=0;i<100;i++){
a[i]=rand()%100;
if(a[i]<60)
count1++;
else if(a[i]>=60&&a[i]<80)
count2++;
else
count3++;
}
for(i=0;i<100;i++){
if(i%5==0)
printf("\n");
printf(" %d ",a[i]);
}
printf("\n count1=%d,count2=%d,count3=%d\n",count1,count2,count3);
/*5.从键盘输入一行字符，统计出字母，数字，空格及其他字符的个数*/
char c[80],i=0,letter,digit,space,other;
letter=digit=space=other=0;
while((c[i]=getchar())!='\n'){
if(c[i]>='a'&&c[i]<='z'||c[i]>='A'&&c[i]<='Z')
letter++;
else if(c[i]>='0'&&c[i]<='9')
digit++;
else if(c[i]=' ')
space++;
else
other++;
i=i+1;
}
printf("letter=%d,digit=%d,space=%d,other=%d",letter,digit,space,other);
/*6.求两个数的最大公约数和最小公倍数*/
int m,n,nm,r,t;
printf("Please input m,n:");
scanf("%d",&m);
scanf("%d",&n);
nm=m*n;
if(m<n){
t=m;
m=n;
n=t;
}
r=m%n;
while(r!=0){
m=n;
n=r;
r=m%n;
}
printf("最大公约数=%d\n",n);
printf("最小公倍数=%d",nm/n);
/*7.输入一个整数，判断是否是素数*/
int m;
printf("请输入一个数：");
scanf("%d",&m);
if(prime(m))
printf("是素数");
else
printf("不是素数");
/*8.一个数如果恰好等于他的因子之和，这个数就称为完数*/
int i,a[1000],j;
for(i=1;i<=1000;i++){
for(j=0;j<1000;j++)
a[j]=0;
if(isPerfect(i,a)){
printf("%d its factors are ",i);
j=0;
while(a[j]!=0)
printf("%d ,",a[j++]);
printf("\n");
}
}
/*9.选择排序法*/
int a[10],i;
printf("Please input 10 numbers:");
for(i=0;i<10;i++){
scanf("%d",&a[i]);
}
selectSort(a,10);
printf("After sorted:");
for(i=0;i<10;i++){
printf("%d ",a[i]);
}
printf("\n");
/*10.冒泡排序法*/
int a[10],i;
printf("Please input 10 numbers:");
for(i=0;i<10;i++){
scanf("%d",&a[i]);
}
bubbleSort(a,10);
printf("After sorted:");
for(i=0;i<10;i++){
printf("%d ",a[i]);
}
printf("\n");
/*11.折半查询法*/
int a[10]={1,3,4,6,9,12,45,56,78,98,};
int result,x;
printf("Please input x:");
scanf("%d",&x);
result=search(a,10,x);
if(result==-1)
printf("%d is not found!",x);
else
printf("%d is in the %d position of array ",x,result);
/*12求二维数组中最大元素，所在行，列*/
int max,row,col,i,j;
int a[5][5]={{1,2,3,4,5},
{2,3,4,5,6},
{3,4,5,6,155},
{4,5,112,7,8},
{5,6,7,8,9}
};
printf("Please input array elements:");
for(i=0;i<5;i++){
for(j=0;j<5;j++){
scanf("%d",&a[i][j]);
}
}
max=a[0][0];
row=0;
col=0;
for(i=0;i<=4;i++){
for(j=0;j<=4;j++){
if(a[i][j]>max){
max=a[i][j];
}
row=i;
col=j;
}
}
printf("max=%d,row=%d,col=%d",max,row,col);
/*13.输出杨辉三角形*/
int i,j,a[10][10];
for(i=0;i<10;i++){
a[i][0]=1;
a[i][i]=1;
}
for(i=2;i<10;i++){
for(j=1;j<i;j++){
a[i][j]=a[i-1][j-1]+a[i-1][j];
}
}
for(i=0;i<10;i++){
for(j=0;j<=i;j++){
printf("%6d",a[i][j]);
}
printf("\n");
}
/*14.将一个十进制数转换成k(2-36)进制字符串*/
int n,k;
char str[10]={'\0'};
printf("Please input n,k:");
scanf("%d %d",&n,&k);
converse(n,k,str);
printf("%s",str);
/*15.输入一行字符，统计有多少个单词*/
char string[81];
int i,num=0,word=0;
char c;
gets(string);
for(i=0;(c=string[i])!='\0';i++){
if(c==' ') word=0;
else if(word==0){
word=1;
num++;
}
}
printf("There are %d words int the line.\n",num);
/*16.迭代法*/
float fSqrt(float a){
float x0,x1;
x0=a/2;
x1=0.5*(x0+a/x0);
while(fabs(x1-x0)>0.00001){
x0=x1;
x1=0.5*(x0+a/x0);
}
return 1;
}
/*17.插入法*/
void insert(int a[],int n,int x){
int p,i;
p=0;
while(x>a[p]&&p<=n){
p=p+1;
}
for(i=n-1;i>=p;i--)
a[i+1]=a[i];
a[p]=x;
}
/*18.穷举法*/
int i,j,k;
printf("5元 1元 0.5元\n");
for(i=1;i<=20;i++){
for(j=1;j<=100-i;j++){
k=100-i-j;
if(5*i+1*j+k/2==100&&k%2==0){
printf("%d %d %d\n",i,j,k);
}
}
}
/*19.递归算法*/
long fac(int n){
if(n==1)
return 1;
else
return n*fac(n-1);
}
float pn(float x,int n){
if(n==0)
return 1;
else if(n==1)
return x;
else
return((2*n-1)*x-pn(x,n-1)-(n-1)*pn(n-2,x))/n;
}
/*20.有n个整数，使前后各数顺序向后移动m个位置,最后m个数变成最前面m个数*/
int i,a[15]={1,6,9,8,5,4,3,5,2,4};
fun(a,10,3);
for(i=0;i<10;i++)
printf("%d ",a[i]);
/*21.从键盘输入一个字符，将小写字符转换成大写字母，然后输出到磁盘文件中一!结束输入*/
FILE *fp;
char str[100];
int i=0;
if((fp=fopen("test","w"))==NULL){
printf("cannot open the file\n");
exit(0);
}
printf("please input a string:\n");
gets(str);
while(str[i]!='!'){
if(str[i]>='a'&&str[i]<='z'){
str[i]=str[i]-32;
fputc(str[i],fp);
}
i++;
if(i>strlen(str)) break;
}
fclose(fp);
fp=fopen("test","r");
fgets(str,strlen(str)+1,fp);
printf("%s\n",str);
fclose(fp);
}
int prime(int m){
int i,result;
result=1;
for(i=2;i<=(int)(sqrt(m));i++){
if(m%i==0){
result=0;
break;
}
}
return result;
}
int isPerfect(int n,int a[]){
int i,sum=0,j=0;
for(i=1;i<=n/2;i++)
if(n%i==0){
sum=sum+i;
a[j++]=i;
}
if(sum==n)
return 1;
else
return 0;
}
void selectSort(int a[],int n)
{
int i,min_index,j,temp;
for(i=0; i<n-1; i++)
{
min_index = i;
for(j=i+1; j<n; j++)
{
if(a[j] < a[min_index])
{
min_index = j;
}
}
if( i != min_index)
{
temp = a[i];
a[i] = a[min_index];
a[min_index] = temp;
}
}
}
void bubbleSort(int a[],int n){
int temp,i,j;
for(i=0;i<n-1;i++){
for(j=0;j<n-1-i;j++){
if(a[j]>a[j+1]){
temp=a[j];
a[j]=a[j+1];
a[j+1]=temp;
}
}
}
}
int search(int a[],int n,int x){
int bot,top,mid;
int find;
bot=0;
top=n-1;
find=-1;
while(bot<=top&&find==-1){
mid=(top+bot)/2;
if(x==a[mid]){
find=mid;
break;
}else if(x<a[mid]){
top=mid-1;
}else{
bot=mid+1;
}
}
return find;
}
void converse(int n,int k,char st[]){
int r,j,i;
char temp;
i=0;
while(n!=0){
r=n%k;
if(r>=10){
st[i++]=65+r-10;
} else{
st[i++]=r+48;
}
n=n/k;
}
}
void fun(int *p,int n,int m){
int b[10],i;
for(i=0;i<m;i++)
b[i]=*(p+n-m+i);
for(i=n-m-1;i>=0;i--)
*(p+i+m)=*(p+i);
for(i=0;i<m;i++)
*(p+i)=b[i];
}

C语言基础：常见算法