Contains Duplicate

Given an array of integers, output 1 if any value appears more than once in the array, otherwise output 0. Use a hash set to track values seen so far: as you scan, if the current value is already in the set the array contains a duplicate; otherwise record it. Batch IO: line 1 is the number of cases T; each subsequent line is one case formatted as "n v1 v2 ... vn" (the array length followed by its n integers). Print exactly T lines, one answer (1 or 0) per case.

func containsDuplicate(nums []int) int {
	seen := make(map[int]bool)
	for _, v := range nums {
			return 1
		}
		seen[v] = true
	}
}

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