ch4

4-11.c

#include <stdio.h>

void main(void){
	int c, i, s, f = 1;

	scanf("%d", &c);
	while(c--){
		printf("%d: \n> ", c);
		scanf("%d", &i);
		if(f){
		        f *= 0;
			s = i;
		}else if(s > i){
			s = i;
		}
	}
	printf("ans：%d\n", s);
}

4-15.c

#include <stdio.h>

double pow(double a, int b){
	double ans = 1.0;
	while(b--){
		ans *= a;
	}
	return ans;
}

void count(double rate){
	double amo, pri = 1000.0;
	int year;
	
	printf("%4s%21s\n", "Year", "Amount on deposit");

	for(year = 1; year <= 10; year++){
		amo = pri * pow(1.0 + rate, year);
		printf("%4d%21.2f\n", year, amo);
	}
	printf("===========================\n");
}

void main(void){
	double i;
	for(i=0.05; i<=0.10; i+=0.01){
		count(i);
	}	
}

4-19.c

#include <stdio.h>

void main(void){
	int id, num;
	double ans = 0;
	
	scanf("%d %d", &id, &num);
	
	switch(id){
		case 1:
			ans = 2.89;
			break;
		case 2:
			ans = 4.50;
			break;
		case 3:
			ans = 9.98;
			break;
		case 4:
			ans = 4.49; 
			break;
		case 5:
			ans = 6.87; 
			break;
	}

	ans *= num;

	printf("%f\n", ans);
}

4-25.c

#include <stdio.h>
#include <string.h>

void convert(char *ans, int num, int n){
	int counter = 0, len;
	while(num){
		len = strlen(ans);
		while(len--){
			ans[len+1] = ans[len];
		}

		ans[0] = num % n;
		ans[0] = ans[0] >= 10? ans[0] + 55: ans[0] + 48;
		ans[counter+1] = 0;
		num /= n;
		counter++;
	}
}

void main(void){
	char ans[80];
	int a[3] = {2, 12, 10}, 
	    counter,
	    i;

	counter = 3;
	while(counter--){
		printf("%d\t", a[counter]);
	}
	printf("\n========================\n");

	for(i = 128; i <= 192; i++){
		counter = 3;
		while(counter--){
			convert(ans, i, a[counter]);
			printf("%s\t", ans);
		}
		printf("\n");
	}
}

4-27.c

#include <stdio.h>

int in(int *h, int s2, int size){
	while(size--){
		if(h[size] == s2){
			return 1;
		}
	}
	return 0;
}

void main(void){
	int i = 100, s1, s2, size = 0;
	while(i){
		int h[80] = {0};
		s1 = i - 1;
		size = 0;
		while(s1){
			s2 = i - 1;
			while(s2){
				if(i * i == s1 * s1 + s2 * s2 && ! in(h, s2, size)){
					h[size] = s1;
					size++;
					printf("斜邊: %d  \t%d\t%d\n", i, s1, s2);
					break;
				}
				s2--;
			}
			s1--;
		}
		i--;
	}
}

7.c

#include <stdio.h>

int CountMonthDays(int y, int m){
	int big[6] = {1, 3, 5, 7, 8, 11},
	    i = 6;

	if(m == 2){
		return y % 4 == 0? 29: 28;
	}
	
	while(i--){
		if(big[i] == m){
			return 31;
		}
	}

	return 30;
}

void main(void){
	int days, y, m, i, fd;
	char *week[] = {"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"};
	
	while(1){
		printf("輸入年：\n> ");
		scanf("%d", &y);
		printf("輸入月：\n> ");
		scanf("%d", &m);
		printf("輸入第一日：\n> ");
		scanf("%d", &fd);
		
		printf("\n");
		i = 7;
		while(i--){
			printf("%s \t", *(week + 6 - i));
		}
		printf("\n");

		i = fd;
		while(i--){
			printf("\t");
		}

		days = CountMonthDays(y, m);
		
		i = days;
		while(i--){
			printf("%d\t", days - i);
			if(fd == 6){
				fd = 0;
				printf("\n");
				continue;
			}
			fd++;
		}
		printf("\n\n");

	}
	
}

8.c

#include <stdio.h>

int CountMonthDays(int y, int m){
	int big[7] = {1, 3, 5, 7, 8, 10, 12},
	    i = 7;

	if(m == 2){
		return y % 4 == 0? 29: 28;
	}
	
	while(i--){
		if(big[i] == m){
			return 31;
		}
	}

	return 30;
}

int CountLeapDays(int y, int m, int d){
	int ans, t1;
	t1 = y - 2000;
	ans = t1 / 4 + 1;
	t1 %= 4;
	if(! t1 && m <= 2 && d < 29){
		ans -= 1;
	}
	return ans;
}

int main(void){
	int i, j, y, t1, t2,
	    M[12] = {5, 1, 1, 4, 6, 2, 4, 0, 3, 5, 1, 3};
	char *week[] = {"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"};

	printf("輸入年：\n> ");
	scanf("%d", &y);
	
	i = 12;
	while(i--){
		printf("\n\n%d月\n", 12 - i);
		
		j = 7;
		while(j--){
			printf("%s \t", *(week + 6 - j));
		}
		printf("\n");

		t1 = (y - 2000 + CountLeapDays(y, 11 - i, 1) + M[11 - i] + 1) % 7;
		
		j = t1;
		while(j--){
			printf("\t");
		}
		
		t2 = CountMonthDays(y, 12 - i);
		j = t2;
		while(j--){
			printf("%d\t", t2 - j);
			if(t1 == 6){
				printf("\n");
				t1 = 0;
				continue;
			}
			t1++;
		}
		printf("\n");
	}

}