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- // O(sqrt(x)) Exhaustive Primality Test
- bool IsPrimeSlow (LL x)
- {
- if(x<=1) return false;
- if(x<=3) return true;
- if (!(x%2) || !(x%3)) return false;
- LL s=(LL)(sqrt((double)(x))+EPS);
- for(LL i=5;i<=s;i+=6)
- {
- if (!(x%i) || !(x%(i+2))) return false;
- }
- return true;
- }
- // Primes less than 1000:
- // 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
- // 439 443 449 457 461 463 467 479 487 491 499 503
- // 509 521 523 541 547 557 563 569 571 577 587 593
- // 599 601 607 613 617 619 631 641 643 647 653 659
- // 661 673 677 683 691 701 709 719 727 733 739 743
- // 751 757 761 769 773 787 797 809 811 821 823 827
- // 829 839 853 857 859 863 877 881 883 887 907 911
- // 919 929 937 941 947 953 967 971 977 983 991 997
- // Other primes:
- // The largest prime smaller than 10 is 7.
- // 100 is 97.
- // 1000 is 997.
- // 10000 is 9973.
- // 100000 is 99991.
- // 1000000 is 999983.
- // 10000000 is 9999991.
- // 100000000 is 99999989.
- // 1000000000 is 999999937.
- // 10000000000 is 9999999967.
- // 100000000000 is 99999999977.
- // 1000000000000 is 999999999989.
- // 10000000000000 is 9999999999971.
- // 100000000000000 is 99999999999973.
- // 1000000000000000 is 999999999999989.
- // 10000000000000000 is 9999999999999937.
- // 100000000000000000 is 99999999999999997.
- // 1000000000000000000 is 999999999999999989.
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