Given2*n + 1numbers, every numbers occurs twice except one, find it.
Example
Given[1,2,2,1,3,4,3], return4
Challenge
One-pass, constant extra space.
这题利用的是异或的性质。loop一遍O(n)做完。
public int singleNumber(int[] A) {
if(A==null||A.length==0){
return 0;
}
int result = 0;
for(int i=0;i<A.length;i++){
result = result^A[i];
}
return result;
}