LeetCode 219. Contains Duplicate II

最新推荐文章于 2024-11-18 11:37:38 发布

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最新推荐文章于 2024-11-18 11:37:38 发布

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本文介绍了如何通过哈希表来解决寻找数组中两个相等元素且它们之间的索引差值不大于给定整数k的问题。通过遍历数组并利用哈希表记录元素出现的位置，我们能够高效地找到符合条件的元素对。

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Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and the difference between i and j is at most k.

#include <vector>
#include <unordered_map>
#include <iostream>
using namespace std;

// Given an array of integers and integer k, find out whether there are two distinct 
// indices i and j in the array such that nums[i] == nums[j] and the difference between i and j is at most k.

// use hashmap.
bool containsNearbyDuplicate(vector<int>& nums, int k) {
    if(nums.size() <= 1) return false;
    unordered_map<int, int> dataToIndex;
    for(int i = 0; i < nums.size(); ++i) {
        auto iter = dataToIndex.find(nums[i]);
        if(iter == dataToIndex.end()) {
            dataToIndex.insert({nums[i], i});
        } else {
            if(i - iter->second  <= k) {return true;}
            else {iter->second = i;}
        }
    }
    return false;
}

int main(void) {
    vector<int> nums{-1, -1};
    bool len = containsNearbyDuplicate(nums, 1);
    cout << len << endl;
}