219. Contains Duplicate II

problem

solution1

class Solution {
public:
    bool containsNearbyDuplicate(vector<int>& nums, int k) {
        for(int i=0; i<nums.size(); i++)//err
        {
            for(int j=i+1; j<nums.size(); j++)
            {
                if(nums[i]==nums[j] && j-i<=k) return true;
            }
        }
        return false;
        
    }
};

View Code

Time Limit Exceeded

solution2:MAP

Hashmap

class Solution {
public:
    bool containsNearbyDuplicate(vector<int>& nums, int k) {
        map<int, int> hashmap;
        for(int i=0; i<nums.size(); i++)
        {
            if(hashmap.find(nums[i])!=hashmap.end() && i-hashmap[nums[i]]<=k) 
            {
                return true;
            }
            hashmap[nums[i]] = i;
        }
        return false;
    }
};

View Code

solution3:SET

class Solution {
public:
    bool containsNearbyDuplicate(vector<int>& nums, int k) {
        set<int> myset;
        for(int i=0; i<nums.size(); i++)
        {
            if(i>k) myset.erase(nums[i-k-1]);
            if(myset.find(nums[i])!=myset.end()) return true;
            myset.insert(nums[i]);//
        }
        return false;
    }
};

参考

1. Leetcode_Contains Duplicate II;

2. CSDN;

完