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32 lines
1.3 KiB
Markdown
32 lines
1.3 KiB
Markdown
# [219. Contains Duplicate II](https://leetcode.com/problems/contains-duplicate-ii/description/)
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# 思路
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判断数组是否有重复元素，而且重复元素下标差的绝对值不大于k，首先简单的思路就是用map，这里给出另一种解法:
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定义一个结构体num_with_index记录数组元素的值和下标，然后再对结构体按照值进行排序，排序后重复元素肯定相邻，再判断下标是否满足条件即可。
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# C++
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```
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class Solution {
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struct num_with_index{
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int num;
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int index;
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};
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public:
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// 这里必须加static否则编译不过，原因参考https://www.cnblogs.com/scoyer/p/6533685.html
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static bool mycompare(const num_with_index &a, const num_with_index &b){
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return a.num > b.num;
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}
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bool containsNearbyDuplicate(vector<int>& nums, int k) {
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vector<num_with_index>newnums;
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num_with_index newnum;
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for(int i = 0; i < nums.size(); i++){
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newnum.num = nums[i];
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newnum.index = i;
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newnums.push_back(newnum);
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}
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sort(newnums.begin(), newnums.end(), mycompare);
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for(int i = 1; i < nums.size(); i++)
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if(newnums[i].num == newnums[i-1].num && abs(newnums[i].index - newnums[i-1].index) <= k) return true;
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return false;
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}
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};
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```
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