王瀚 second submission

homework2017.2.26/p01_runningLetter.cpp

@@ -0,0 +1,20 @@
+#include<stdio.h>
+#include<stdlib.h>
+int main()
+{
+	const int lenth=80;
+	int len_now=0,goBack=0,step;
+	while (1)
+	{
+		system("cls");
+		for (step=1;step<len_now;step++)
+			printf(" ");
+		printf("R");
+		if (goBack) len_now--;
+		else len_now++;
+		if (len_now==lenth)	goBack=1;
+		else if (len_now==0)	goBack=0;
+		sleep(50);
+	}
+	return 0;
+}

homework2017.2.26/p02_isPrime.cpp

@@ -0,0 +1,21 @@
+#include<stdio.h>
+int main(){
+	int number,i;
+	while (scanf("%d",&number)!=EOF){	
+		if (number==0){
+			break;
+		}
+		for (i=2;i*i<=number;i++){
+			if (number%i==0){
+				break;
+			}
+		}
+		if (i*i>number){
+			printf("Yes\n");	
+		}
+		else{
+			printf("No\n");
+		}
+	}
+	return 0;
+}

homework2017.2.26/p03_Diophantus.cpp

@@ -0,0 +1,11 @@
+#include<stdio.h>
+int main(){
+ 	int age=1;
+ 	while (age++){
+ 		if (age%6==0&&age%12==0&&age%7==0&&(age/2-age/6-age/12-age/7)==9)	{
+			break;
+		}	
+	}
+	printf("%d\n",age-4);
+	return 0;
+}

homework2017.2.26/p04_narcissus.cpp

@@ -0,0 +1,14 @@
+#include<stdio.h>
+int main(){
+ 	int number;
+ 	int hundred,ten,one;
+ 	for (number=100;number<=999;number++){
+ 		hundred=number/100;
+ 		ten=(number/10)%10;
+ 		one=number%10;
+ 		if (number==hundred*hundred*hundred+ten*ten*ten+one*one*one){
+			printf("%d\n",number);
+		}
+	}
+	return 0;
+ }

homework2017.2.26/p05_allPrimes.cpp

@@ -0,0 +1,26 @@
+#include<stdio.h>
+#include<string.h>
+#include<time.h>
+int main(){
+ 	int i,j=2,prime[1000],numb;
+ 	clock_t start,endd;
+	start=clock();
+	memset(prime,0,sizeof(prime));
+	prime[1]=2;
+ 	printf("%d\n",prime[1]);
+ 	for (numb=3;numb<=1000;numb++){
+ 		for (i=1;prime[i]*prime[i]<=numb&&prime[i];i++){
+			if (numb%prime[i]==0){
+				break;
+			}
+		}
+		if(prime[i]*prime[i]>numb){
+			prime[j++]=numb;
+		 	printf("%d\n",numb);
+		}
+	}
+	endd=clock();
+	printf("The algorithm costs %.0lfms;\n",(double)(endd-start));
+	printf("It will costs 0.01ms without printf().\n");
+ 	return 0;
+}

homework2017.2.26/p06_Goldbach.cpp

@@ -0,0 +1,35 @@
+#include<stdio.h>
+int main(){
+  	int i,j=2,numb,prime[100];
+ 	prime[1]=2;
+ 	for (numb=3;numb<=100;numb++){
+ 		for (i=1;prime[i]*prime[i]<=numb&&prime[i];i++){
+			if (numb%prime[i]==0)	break;			
+		}
+		if(prime[i]*prime[i]>numb){
+			prime[j++]=numb;			
+		}
+	}
+	for (numb=4;numb<=100;numb+=2){
+		for (i=1;prime[i]!=0;i++){
+			for (j=1;prime[j]!=0;j++){
+				if (prime[j]+prime[i]==numb){
+					break;		
+				}			
+			}
+			if (prime[j]==0){
+				break;	
+			}
+		}
+		if (prime[i]==0&&prime[j]==0){
+			break;
+		}
+	}
+	if (numb>100){
+		printf("proved\n");
+	}
+	else{
+		printf("not");	
+	}
+	return 0;
+}