499 123 456 789
499是三位数
<=499的素数有:
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 101 103 107 109 113 127 131 137 139 149 151 157 163 167 173 179 181 191 193 197 199 211 223 227 229 233 239 241 251 257 263 269 271 277 281 283 293 307 311 313 317 331 337 347 349 353 359 367 373 379 383 389 397 401 409 419 421 431 433 439 443 449 457 461 463 467 479 487 491 499
<=499的水仙花有:
153 370 371 407

1 3 5 7 9
1不是三位数
是等差序列，公差:2

2 4 8 16 32
2不是三位数
是等比序列，公比:2

2 14 18 116 32
2不是三位数
三种情况全不是。

#include <stdio.h>
#include <math.h> int len(int num)
{int cnt = 0;while (num) {cnt += 1;num /= 10;}return cnt;
}int isPrime(int n) {if (n < 2)return 0;for (int i = 2; i <= n / 2; i++)if (n % i == 0)return 0;return 1;
}int isShuXianHua(int n) {int g, s, b;g = n % 10;s = n / 10 % 10;b = n / 100;return g * g * g + s * s * s + b * b * b == n;
}
void print(int a[], int n) {for (int i = 0; i < n; i++)printf("%d ",a[i]);printf("\n");
}
int fun(int a[], int n) {print(a,n);if (len(a[0]) == 3) {printf("%d是三位数\n",a[0]);printf("<=%d的素数有:\n",a[0]);for (int i = 2; i <= a[0]; i++)if (isPrime(i))printf("%d ",i);printf("\n");printf("<=%d的水仙花有:\n", a[0]);for (int i = 100; i <= a[0]; i++)if (isShuXianHua(i))printf("%d ", i);printf("\n");}else {printf("%d不是三位数\n", a[0]);int d = a[1] - a[0];int isD = 1;for(int i=1;i<n;i++)if (a[i - 1] + d != a[i]) {isD = 0;break;}if (isD) {printf("是等差序列，公差:%d\n",d);}else {int p = a[1] / a[0];int isP = 1;for (int i = 1; i < n; i++)if (a[i - 1] * p != a[i]) {isP = 0;break;}if (isP) {printf("是等比序列，公比:%d\n", p);}else {printf("三种情况全不是。\n");}}}puts("");
}int main() {int a[4] = {499,123,456,789};int b[5] = { 1,3,5,7,9 };int c[5] = { 2,4,8,16,32 };int d[5] = { 2,14,18,116,32 };fun(a,4);fun(b,5);fun(c,5);fun(d, 5);}