Contains Duplicate II

​​https://leetcode.com/problems/contains-duplicate-ii/​​

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.

这道题目源自 [Contains Duplicate] (​​javascript:void(0)​​)

不同的是查找到的两个相同元素的下标距离不能超过给定的参数K。所以可以把上个题目改进一下，创建一个index数组，将nums数组元素排序前后的index关系映射存储起来，比如有个元素3的原先的下标是 i，排序过后的下表到了数组的位置j， 则有 index[j]=i;

bool containsNearbyDuplicate(int* nums, int numsSize, int k) {
    int i, j, key;
    int *index = (int *)malloc(numsSize * sizeof(int));  // store index
    //memset(index, 0, numsSize * sizeof(int));

    for(i = 1; i < numsSize; ++i) {
       j = i - 1;
       key = nums[i];
       while(j > 0 && nums[j] > key) {
           nums[j + 1] = nums[j];   // move to back
           index[j + 1] = index[j];
           j--;
       }

       //if(j != (i-1)) 
       //{
            nums[j + 1] = key;
            index[j + 1] = i;   // map new index to old
       //}

        /* check */
        if((nums[j] == key) && (i - index[j] <= k)) 
            return true;
   }

   free(index);

    return  false;
}