笔试算法题（34）：从数字序列中寻找仅出现一次的数字 & 最大公约数（GCD）问题

 1 int findSingleInt(int *array, int length) {
 2         int result=0;
 3         for(int i=0;i<length;i++)
 4                 result^=array[i];
 5         return result;
 6 }
 7 
 8 int main() {
 9         int array[]={1,2,3,4,5,1,2,3,4,5,6};
10         printf("%d\n",findSingleInt(array,11));
11         return 0;
12 }

 1 int gcd1(int x, int y) {
 2         return (y==0) ? x:gcd1(y,x%y);
 3 }
 4 
 5 int gcd2(int x, int y) {
 6         if(x<y)
 7                 return gcd2(y,x);
 8         if(y==0)
 9                 return x;
10         else
11                 return gcd2(x-y,y);
12 }
13 
14 int gcd3(int x, int y) {
15         if(x<y)
16                 return gcd3(y,x);
17         if(y==0)
18                 return x;
19         else {
20                 if(x%2==0) {
21                         if(y%2==0)
22                                 return (gcd3(x >> 1, y >> 1) << 1);
23                         else
24                                 return gcd3(x >> 1,y);
25                 } else {
26                         if(y%2==0)
27                                 return gcd3(x,y >> 1);
28                         else
29                                 return gcd3(y,x-y);
30                 }
31         }
32 }