Homework

level1/p01_runningLetter/runningLetter.c

@@ -0,0 +1,33 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+
+void main() {
+    int n = 0;
+    const int right_border = 105, left_border = 0;
+    char value = 1;//value为1时向右移动，否则向左移动 
+    while (1) {
+        if (value) {
+            for (int i = 0; i < n; i++) {
+                printf(" ");
+            }
+            printf("Running Word");
+            n++;
+            system("cls");//清屏 
+            if (n == right_border) {
+                value = 0;
+            }
+        }
+        else {
+            for (int i = 0; i < n; i++) {
+                printf(" ");
+            }
+            printf("Running Word");
+            n--;
+            system("cls");
+            if (n == left_border) {
+                value = 1;
+            }
+        }
+    }
+}

level1/p02_isPrime/isprime.c

@@ -0,0 +1,23 @@
+#include <stdio.h>
+#include <math.h>
+
+int is_prime(int n){
+	int i;
+	for(i=2;i<=sqrt(n);i++){
+		if(n%i==0){
+			return 0;
+		}	
+	}
+	return 1;
+} 
+
+int main(){
+	int n;
+	printf("Please enter a number: ");
+	scanf("%d",&n);
+	if(is_prime(n)&&n>1){
+		printf("It is a prime number.");
+	}else{
+		printf("It isn't a prime number.'");
+	}
+}

level1/p03_Diophantus/Diophantus.c

@@ -0,0 +1,12 @@
+#include <stdio.h>
+//����ͼ���� 
+int main(){
+	float x;
+	for(x=1;x<200;x++){
+		if((x/6+x/12+x/7+5+x/2+4)==x){
+			printf("%.0f",x);
+			break;
+		}
+	}
+	return 0;
+} 

level1/p04_ narcissus/narcissus.c

@@ -0,0 +1,14 @@
+#include <stdio.h>
+
+int main(){
+	int n;
+	int a,b,c;
+	for(n=100;n<1000;n++){
+		c = n%10;//���
+		b = n/10%10;//ʮλ��
+		a = n/100;//���
+		if((a*a*a+b*b*b+c*c*c)==n){
+			printf("%d\n",n);
+		}
+	}
+}

level1/p05_allPrimes/allPrimes.c

@@ -0,0 +1,64 @@
+#include <stdio.h>
+#include <math.h>
+#include <time.h>
+
+//�������� 
+int is_prime1(){
+	int i,n,m,t = 0;
+	for(n = 2;n < 1000;n ++){
+		m = 1;
+		for(i = 2;i <= sqrt(n);i ++){
+			if(n % i == 0){
+				m = 0;
+				break;
+			}
+		}
+		if(m == 1){
+			printf("%d\t",n);
+			t ++;
+		}
+		if(t == 15){
+			printf("\n");
+			t = 0;
+		}
+	}
+	return 0;
+}
+
+//����ɸ 
+int is_prime2(){
+	char a[1000] = {1};
+	int i,x,m = 0;
+	for(i = 2;i < 1000;i ++){
+		if(a[i] == 0){
+			for(x = i*i;x < 1000;x = x + i)a[x] = 1;
+			printf("%d\t",i);
+			m ++;
+			if(m == 15){
+				printf("\n");
+				m = 0;
+			}
+		}
+	}
+}
+
+int main(){
+	int n,m = 0;
+	clock_t start_t,end_t;
+	double total_t;
+
+	//�������� 
+	start_t = clock();
+	is_prime1();
+	end_t=clock();
+	total_t = (double)(end_t - start_t) / CLOCKS_PER_SEC;
+	printf("\n�������е���ʱ��Ϊ: %fs\n",total_t);
+
+	//����ɸ 
+	start_t = clock();
+	is_prime2();
+	end_t = clock();
+	total_t = (double)(end_t - start_t) / CLOCKS_PER_SEC;
+	printf("\n�������е���ʱ��Ϊ: %fs",total_t);
+	return 0;
+}

level1/p06_Goldbach/Goldbach.c

@@ -0,0 +1,26 @@
+#include <stdio.h>
+#include <math.h>
+#include <stdbool.h>
+
+bool is_prime(int n){
+	int i;
+	for(i=2;i<=sqrt(n);i++){
+		if(n%i==0)return false;
+	}
+	return true;
+}
+
+int main(){
+	int n,m,x=0;
+	for(n = 4;n <= 100;n += 2){
+		for(m = 2;m <= n;m ++){
+			if(is_prime(m) && is_prime(n - m)){
+				printf("%3d = %2d + %2d\n",n,m,n - m);
+				x++;
+				break;
+			}
+		}
+		if(x==49)printf("The Goldbach is true");
+	}
+	return 0;
+}