Question

1-200内有多少个质数？

Answer 1

#include<stdio.h>

#include<math.h>

int sushu(int num)

{

int nGen = sqrt(num) + 1;

if (num <= 1)

return -1;

if (num == 2)

return 1;

else if (num % 2 == 0)

return 0;

else

{

int i = 3;

do

{

if (num%i == 0)  //如果除以5,7,9...能整除,则不是素数

return 0;

else

i += 2;

} while (i <=  nGen);

return 1;

}

}

int main()

{

int n = 1, flag = 0;

while (n <= 200)

{

if (sushu(n) == 1)

{ 

printf("%8d",n);

flag += 1;

}

++n;

}

printf("有%d个素数",flag);

return 0;

}

Answer 2

2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 101 103 107 109 113 127 131 137 139 149 151 157 163 167 173 179 181 191 193 197 199

Answer 3

2
3
5
7
11
13
17
19
23
29
31
37
41
43
47
53
57
59
61
67
71
73
79
83
87
91
97

Answer 4

27个