Finished Homework

level1/p01_runningLetter/running-letter.cpp

@@ -0,0 +1,26 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <windows.h>
+
+void print_1(int i)
+{
+	int j=0;
+	while (j<i) {printf(" ");j++;}
+}
+
+void print_2(int i)
+{
+	print_1(i);
+	printf("C\n");
+	Sleep(70);
+	system("cls");
+}
+
+int main()
+{
+	int i;
+	system("mode con cols=101 lines=30  ");
+	for (i=0;i<=100;i++) print_2(i);
+	for (i=100;i>=0;i--) print_2(i);
+	return 0;
+}

level1/p02_isPrime/isPrime.cpp

@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include <math.h>
+
+int judge(int num)
+{
+	int i,judge=0;
+	for (i=2;i<=sqrt(num);i++)
+	{
+		judge=num%i;
+		if (judge==0)
+		{
+			break;
+		}
+		else continue;
+	}
+	if (num==2||num==3)
+	{
+		judge=1;
+	}
+	return judge;
+}
+
+int main()
+{
+	int num;
+	printf("Please enter a nunber:\n");
+	scanf("%d",&num);
+	if (judge(num)==0) 
+	{
+		printf("%d is not a prime number.\n",num);
+	}
+	else
+	{
+		printf("%d is a prime number.\n",num);
+	}
+	return 0;
+}

level1/p03_Diophantus/Diophantus.cpp

@@ -0,0 +1,15 @@
+#include<stdio.h>
+
+int main()
+{
+	int x;
+	for (x=1;x<200;x++)
+	{
+		if ((x/6.0+x/12.0+x/7.0+5+x/2.0+4)==(x/1.0))
+		{
+			printf("Diophantus was %d years old\n",x);
+		}
+		else continue;
+	}
+	return 0;
+}

level1/p04_ narcissus/narcissus.cpp

@@ -0,0 +1,30 @@
+# include <stdio.h>
+# include <math.h>
+
+int judge(int n)
+{
+	int unit,tens,hundreds,m=n;
+	hundreds=n/100;
+	n-=hundreds*100;
+	tens=n/10;
+	unit=n-tens*10;
+	if ((pow(unit,3)+pow(tens,3)+pow(hundreds,3))==m)
+	{
+		return 1;
+	}
+	else return 0;
+}
+
+int main()
+{
+	int i;
+	for (i=100;i<1000;i++)
+	{
+		if(judge(i)==1)
+		{
+			printf("%-4d",i);
+		}
+		else continue;
+	}
+	return 0;
+}

level1/p05_allPrimes/allPrimes.cpp

@@ -0,0 +1,41 @@
+#include <stdio.h>
+#include <time.h>
+
+int judge(int num)
+{
+	int i,judge=0;
+	for (i=2;i<(num/2+1);i++)
+	{
+		judge=num%i;
+		if (judge==0)
+		{
+			break;
+		}
+		else continue;
+	}
+	if (num==2||num==3)
+	{
+		judge=1;
+	}
+	return judge;
+}
+
+int main()
+{
+	int a=clock();
+	int i,c;
+	for (i=2;i<1000;i++)
+	{
+		if (judge(i)==0) 
+		{
+			continue;
+		}
+		else
+		{
+			printf("%-4d",i);
+		}
+	}
+	int b=clock();
+	printf ("\nRunning time:%d ms",c=b-a);
+	return 0;
+}

level1/p06_Goldbach/Goldbach.cpp

@@ -0,0 +1,42 @@
+#include <stdio.h>
+#include <math.h>
+
+int judge(int num)
+{
+	int i,judge=0;
+	for (i=2;i<(sqrt(num)+1);i++)
+	{
+		judge=num%i;
+		if (judge==0)
+		{
+			break;
+		}
+		else continue;
+	}
+	if (num==2||num==3)
+	{
+		judge=1;
+	}
+	return judge;
+}
+
+int main()
+{
+	int n,i,j;
+	printf("Please enter the range:\n");
+	scanf("%d",&j);
+	for (n=4;n<=j;n+=2)
+	{
+		for (i=2;i<n;i++)
+		{
+			if (((judge(i)!=0)) && ((judge(n-i))!=0))
+			{
+				printf("%d = %d+%d \n",n,i,(n-i));
+				break;
+			}
+			else continue;
+		}
+	}
+	return 0;
+}
+

level1/p07_encrypt_decrypt/encrypt-decrypt.cpp

@@ -0,0 +1,39 @@
+#include<stdio.h>
+#define K 2
+
+void encrypt(char *p)
+{
+	for (int i=0;i<100;i++,p++)
+	{
+		if ((*p)=='\0')
+		{break;}
+		(*p)+=K;
+		printf("%c",*p);
+	}
+}
+
+void decrypt(char *p)
+{
+	for (int i=0;i<100;i++,p++)
+	{
+		if ((*p)=='\0')
+		{break;}
+		(*p)-=K;
+		printf("%c",*p);
+	}
+}
+
+int main()
+{
+	int n;
+	void (*p1)(char *);
+	char ch[100];
+	printf("Please choose 1 or 2(1--encrypt, 2--decrypt) :\n");
+	scanf("%d",&n);
+	printf("Please enter your text:\n");
+	scanf("%s",ch);
+	(n==1) ? p1=encrypt :p1=decrypt;
+	printf("Result:\n");
+	(*p1)(ch);
+	return 0;
+}

level1/p08_hanoi/hanio.cpp

@@ -0,0 +1,30 @@
+#include <stdio.h>
+
+void move(char x,char y)
+{
+	printf("%c-->%c\n",x,y);
+}
+
+void hanoi(int n,char one,char two,char three)
+{
+	if (n == 1)
+	{
+		move(one,three);
+	}
+	else 
+	{
+		hanoi(n-1,one,three,two);
+		move(one,three);
+		hanoi(n-1,two,one,three);
+	}
+}
+
+int main()
+{
+	int n;
+	printf("Please enter the number of disks:\n");
+	scanf("%d",&n);
+	printf("The steps are as follows:\n");
+	hanoi(n,'A','B','C');
+
+}