Find two occurrences of the number in the array "Microsoft interview 100 question 61st"

Title Requirements:

An integer array except for two digital machines, the other numbers appear two times.

Please write the program to find the two only occurrences of the number. Requires time complexity O (N). Space complexity O (1).

Reference: Sword refers to the 40th question of offer.

Topic Analysis:

Known:

1. Two the same number XOR result is 0, i.e. A^a = 0.

2. Two different numbers xor the result of a binary in which one is 1, then the two digits of the binary corresponding bit one is 0, one is 1. as 3^2 = 1, for the lowest bit binary, the lowest bit binary of 3 is the lowest bit bits 0, then the lowest bit binary of the result 1 is definitely 1.

Assuming that the original array only appears once in the two numbers of A and B, then, the original array of all the elements of the result C, that is, the result of a^b (because the other XOR is 0), that is a^b = C;

according to the known condition 2, we find the second binary in the binary in the bit 1, the original array is divided into two parts x and Y (A and B respectively in X and Y, and X and y respectively are only one number appears once, other numbers appear two times ), The result of all the elements in X will certainly be the result of an XOR of all the elements in the a,y.

Code implementation:

　　

#include <iostream>using namespacestd;Const intN =6;BOOLFindnumsappearonce (intData[],intLenint&AMP;NUM1,int&num2);intMainvoid){    intData[n] = {4,2,6,2,4,5};//int Data[n] = {4,2,6,2,4,6};    intnum1,num2; if(Findnumsappearonce (data,n,num1,num2)) {cout<<"NUM1 ="<< NUM1 <<", num2 ="<< num2 <<Endl; }    Elsecout<<"not satisfied with the situation"<<Endl; return 0;} unsignedintFINDFIRSTBITIS1 (intnum) {    intindex =0;  while((num&1)==0&& (index<8*sizeof(int)) {num>>=1; ++index; }    returnindex;}BOOLIsBit1 (intnum,unsignedintindex) {num>>=index; return(num&1);}BOOLFindnumsappearonce (intData[],intLenint&AMP;NUM1,int&num2) {    if(Data==null | | len<2|| ((len&0x01)==1))        return false; intresult =0;  for(intI=0; i<len;i++) Result^=Data[i]; if(result==0)        return false; unsignedintindex =FindFirstBitIs1 (Result); NUM1= Num2 =0;  for(intj =0; j<len;j++)    {        if(IsBit1 (data[j],index)) Num1^=Data[j]; Elsenum2^=Data[j]; }    return true;}

　　

Find two occurrences of the number in the array "Microsoft interview 100 question 61st"