Contains Duplicate

Given an array of integers, find if the array contains any duplicates. Your function should return true if any value appears at least twice in the array, and it should return false if every element is distinct.

用set结构解决：

class Solution {
public:
    bool containsDuplicate(vector<int>& nums) {
        set<int> temp;
        for(int i=0;i<nums.size();i++){
            if(temp.find(nums[i]) == temp.end()){
                temp.insert(nums[i]);
            }else{
                return true;
            }
        }
        return false;
    }
};

用排序方法解决：

class Solution {
public:
    bool containsDuplicate(vector<int>& nums) {
        sort(nums.begin(),nums.end());
        for(int i=1;i<nums.size();i++){
            if(nums[i-1] == nums[i])
                return true;
        }
        return false;
    }
};