In an array of '75 int' type, except for one or two occurrences, all other occurrences occur three times.

[Link to this article]

Http://www.cnblogs.com/hellogiser/p/single-number-of-array-with-other-three-times.html

[Question]

In an array of the int type, each number appears three times except one or two times.

[Analysis]

C ++ code

1 2 3 4 5 6 7 8 9 10 11 12

Int singlenumber (int * a, int N) { Int ones = 0, twos = 0; For (INT I = 0; I <n; I ++) { Ones = (ones ^ A [I]) & (~ Twos ); Twos = (twos ^ A [I]) & (~ Ones ); } // Ones Return ones; }

When a appears, ones can save. When a appears twice, twos can save. When a appears three times, both ones and twos are cleared. Therefore, if all the numbers in a value are passed through this loop, the three numbers are cleared. If one number exists once, it is stored in ones; if it appears twice, it is saved in twos.

[Code]

 

C ++ code

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92

// 75_onetwonumber_withother3times.cpp: defines the entry point for the console application. // /* Version: 1.0 Author: hellogiser Blog: http://www.cnblogs.com/hellogiser Date: 2014/9/18 */ # Include "stdafx. H" # Include "iostream" Using namespace STD; Void print (int * a, int N) { For (INT I = 0; I <n; I ++) { Cout <A [I] <""; } Cout <Endl; } // ================================================ ====================================== // Single number 1, 1, 2 => 2 // ================================================ ====================================== /* X 1st, ones = x, twos = 0 X 2st, ones = 0, twos = x X 3st, ones = 0, twos = 0 */ Int singlenumber (int * a, int N) { Int ones = 0, twos = 0; For (INT I = 0; I <n; I ++) { Ones = (ones ^ A [I]) & (~ Twos ); Twos = (twos ^ A [I]) & (~ Ones ); } // Ones Return ones; } // ================================================ ====================================== // Double number 1,100,100, 100 ======> // ================================================ ====================================== Int doublenumber (int * a, int N) { Int ones = 0, twos = 0; For (INT I = 0; I <n; I ++) { Ones = (ones ^ A [I]) & (~ Twos ); Twos = (twos ^ A [I]) & (~ Ones ); } // Twos Return twos; } Void test_base_single () { Int A [] = {1, 1, 1, 2 }; Int N = 4; Cout <"array is :"; Print (A, N ); Cout <"single number" <singlenumber (A, n) <Endl; } Void test_base_double () { Int A [] = {1, 1, 1,100,100 }; Int n = 5; Cout <"array is :"; Print (A, N ); Cout <"Double number" <doublenumber (A, n) <Endl; } Void test_main () { Test_base_single (); Test_base_double (); } Int _ tmain (INT argc, _ tchar * argv []) { Test_main (); Return 0; } /* Array is: 1 1 1 2 Single Number 2 Array is: 1 1 100 100 Double number 100 */

In an array of '75 int' type, except for one or two occurrences, all other occurrences occur three times.