# 算法竞赛_入门经典_刘汝佳_（二）

www.MyException.Cn  网友分享于：2014-05-08  浏览：0次

1，有几位数字

```#include<stdio.h>

int main_2_1_digit(){
int n;

while(scanf("%d",&n)){
int count = 0;
if(n==0)
count = 1;
while(n){
count++;
n/=10;
}

printf("%d\n",count);
}
return 0;
}```

2，三位数的三个数字

```#include<stdio.h>

int main_2_2_daffodil(){

int i,j,k;

for(int n=100;n<=999;n++){
i = n % 10;
j = (n/10) % 10;
k = (n/100) % 10;

if( n == i*i*i + j*j*j + k*k*k){
printf("%d\n",n);
}
}

return 0;
}```

3，韩信点兵

```#include<stdio.h>

int main_2_3_hanxin(){

int a,b,c;
int i,sum;

while(scanf("%d%d%d",&a,&b,&c)){
sum = -1;
for(i=10;i<=100;i++){
if(i%3 == a && i%5 == b && i%7 == c){
sum =i;
break;
}
}

if(sum == -1){
}else{
printf("%d\n",sum);
}
}

return 0;
}```

4，打印倒三角

```#include<stdio.h>

int main_2_4_triangle(){

int n;
int i,j;

while(scanf("%d",&n)){

for(i=n;i>0;i--){
for(j=1;j < n;j++){
if(j+i >= n+1){
printf("#");
}else{
printf(" ");
}
}

printf("#");

for(j=n+1;j < 2*n;j++){
if(j-i <= n-1){
printf("#");
}else{
printf(" ");
}
}

printf("\n");
}

}

return 0;
}```

5，输入n个数，比m小的

```#include<stdio.h>

int main_2_5_stat(){
int arr[1000];
int n,m;
int i;
int count;

while(scanf("%d",&n)){
for(i=0;i<n;i++){
scanf("%d",&arr[i]);
}
scanf("%d",&m);

count=0;
for(i=0;i<n;i++){
if(m > arr[i]){
count++;
}
}

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

return 0;
}```

6，数aabb

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

int main_aabb_complete(){

int a,b,n;
double m;

for(a=1;a<=9;a++){
for(b=0;b<=9;b++){
n=a*1100 + b*11;

m=sqrt((double)n);

//判断m是否为整数
//进行浮点数比较的时候要考虑浮点误差
if(floor(m+0.5) == m){
printf("%d     %lf\n",n,m);
}
}
}

getchar();
return 0;
}```

7，浮点数陷阱

```#include<stdio.h>

int main_float_trap(){

double i;

for(i=9;i!=10;i+=0.1){

printf("%.1lf\n",i);

if(i>10){
break;
}
}

return 0;
}```

8，varble_no_init

```#include<stdio.h>

int main_varble_no_init(){

int a,b,c;

printf("%d %d %d",a,b,c);

scanf("%d",&a);

return 0;

}```

9，全排列

```#include<stdio.h>

int n = 0;
void swap(int *a,int *b){
int m = *a;
*a = *b;
*b = m;
}

void perm(int list[],int k,int m){
int i;

if(k > m){
for(i=0;i<=m;i++){
printf("%d ",list[i]);
}
printf("\n");
n++;
}else{
for(i=k;i<=m;i++){
swap(&list[k],&list[i]);
perm(list,k+1,m);
swap(&list[k],&list[i]);
}
}
}

int main_quan_pai_lie_version_1(){
int list[] = {1,2,3,4,5};

perm(list,0,4);

printf("total: %d\n",n);

return 0;
}
```