数组中的重复数字_50

public int duplicate (int[] numbers) {
        // write code here
        int[] count=new int[numbers.length];
        for (int i = 0; i < numbers.length; i++) {
            count[numbers[i]]++;
            if (count[numbers[i]]==2){
                return numbers[i];
            }
        }
        return -1;
    }