一

#include <stdio.h>
int main(){
	int a,b,c,cache;
	printf("请输入三个整数:");
	scanf("%d%d%d",&a,&b,&c);
	if(a>b){	
		cache=a;	
		a=b;	
		b=cache;	
	}
	if(a>c){	
		cache=a;	
		a=c;	
		c=cache;	
	}
	if(b>c){
		cache=b;	
		b=c;	
		c=cache;	
	}
	printf("从小到大排列为:%d,%d,%d",a,b,c);
	return 0;
}  

二

#include<stdio.h>
int main(void)
{
	/*********Begin*********/
	int year;
	scanf("%d",&year);
	if(year%4==0 && year%100!=0||year%400==0) {
		printf("%d 是闰年！",year);
	}
	else {
		printf("%d 不是闰年！",year);
	}


	/*********End**********/
	 return 0;
}

三

#include<stdio.h>
int main(void)
{
	float x,y;
	scanf("%f",&x);
	if(x<0&&x!=-3)
	{
		y=x*x+x-6;
		printf("%.3f",y);
	}
	else if(x>=0&&x<10&&x!=2&&x!=3)
	{
		y=x*x-5*x+6;
		printf("%.3f",y);
	}
	else 
	{
		y=x*x-x-1;
		printf("%.3f",y);
	}
	return 0;
}

四

#include <limits.h>
#include<stdio.h>
int main(void)
{
	/*********Begin*********/
	  int score;
	  scanf("%d",&score);
if(score>100||score<0) {
	printf("Score is error!");
	return 0;
}
	else {
		switch(score/10) {

			case 6:
				printf("D");
			break;
			case 7:
				printf("C");
			break;
			case 8:
				printf("B");
			break;
			case 9:
				printf("A");
			break;
			case 10:
				printf("A");
			break;
			default:
				printf("E");
			break;
		}

	}

	/*********End**********/
	return 0;
}

进阶

一

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

int main(void)
{
    /*********Begin*********/
    int areacode,wet;
    float weight,cost;
    scanf("%d,%f",&areacode,&weight);
    wet=ceil(weight-1);
    switch(areacode){
        case 0:
            cost=10+ceil(weight-1)*3;
        break;
        case 1:
            cost=10+ceil(weight-1)*4;
        break;
        case 2:
            cost=15+ceil(weight-1)*5;
        break;
        case 3:
            cost=15+ceil(weight-1)*6.5;
        break;
        case 4:
            cost=15+ceil(weight-1)*10;
        break;
        default:
            printf("Error in Area\n");
        break;
}
    printf("Price: %.2f\n",cost);
    /*********End**********/
    return 0;
}

二

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

int main(void)
{
    /*********Begin*********/
    double a=0, b=0, c=0,delta=0;
    printf("Please enter the coefficients a,b,c:\n");
    scanf("%lf,%lf,%lf",&a,&b,&c);
    delta = b*b - 4*a*c;
    if(delta<0) {
        printf("error!\n");
    }
    else {
        double root=sqrt(delta);
        double x1 =  (-b + root)/(2*a);
        double x2 =  (-b - root)/(2*a);
        printf("x1=%.4f, x2=%.4f\n",x1,x2);

    }
    /*********End**********/
    return 0;
}

三

#include<stdio.h>
int main(void)
{
    /*********Begin*********/
    printf("Enter item number:\n");
    int code;
    scanf("%d",&code);
    printf("Enter unit price:\n");
    float price;
    scanf("%f",&price);
    printf("Enter purchase date (mm/dd/yy):\n");
    int mm,dd,yy;
    scanf("%d/%d/%d",&mm,&dd,&yy);
    printf("Item Unit Purchase\n");
    printf("%-9d$ %-9.2f%02d%02d%04d\n",code,price,mm,dd,yy);
    
    /*********End**********/
    return 0; 
}