public class TestMethod3_1 {
public static void main(String[] args) {
int[] arr = {2, 3, 1, 0, 2, 5, 3};
System.out.println("打印重複的數字=>" + method(arr));
}
public static int method(int[] arr) {
if (arr == null || arr.length <= 0) return -1;
for (int i = 0; i < arr.length; i++) {
if (arr[i] < 0 || arr[i] > arr.length - 1) return -1;
}
for (int i = 0; i < arr.length; i++) {
while (i != arr[i]) {
if (arr[i] == arr[arr[i]]) return arr[i];
swap(arr, i, arr[i]);
}
}
return -1;
}
public static void swap(int[] arr, int a, int b) {
int temp = arr[a];
arr[a] = arr[b];
arr[b] = temp;
}
}