题目描述:
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 absolute difference between i and j is at most k.
Example 1:
Input: nums = [1,2,3,1], k = 3
Output: true
Example 2:
Input: nums = [1,0,1,1], k = 1
Output: true
Example 3:
Input: nums = [1,2,3,1,2,3], k = 2
Output: false
对于一个数组判断是否存在两个元素数值相等,而且下标相差不超过k,还是利用哈希表记录数值上一次出现的下标,当这个数值再次出现进行比较即可。
class Solution {
public:
bool containsNearbyDuplicate(vector<int>& nums, int k) {
unordered_map<int,int> hash;
for(int i=0;i<nums.size();i++)
{
if(hash.count(nums[i])==0) hash[nums[i]]=i;
else
{
if(i-hash[nums[i]]<=k) return true;
else hash[nums[i]]=i;
}
}
return false;
}
};