# 217. Contains Duplicate PonPon === ``` c= int cmp(const void *a, const void *b){ return *(int*)a-*(int*)b; } bool containsDuplicate(int* nums, int numsSize){ int i=0, j=0; if (numsSize == 1) return false; qsort(nums, numsSize, sizeof(int), cmp); for (i=0;i<numsSize-1;i++) { if (nums[i] == nums[i+1]) return true; } return false; } time complexity: O(n log n) space complexity: O(1) Comment: Search qsort in web, need to implement merge sort ```