contains-duplicate-ii.cpp

// 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.
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// Example 1:
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// Input: nums = [1,2,3,1], k = 3
// Output: true
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// Example 2:
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// Input: nums = [1,0,1,1], k = 1
// Output: true
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// Example 3:
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// Input: nums = [1,2,3,1,2,3], k = 2
// Output: false
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//


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