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S50.java
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S50.java
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package S41_50;
import java.util.HashSet;
import java.util.Set;
/**
* 数组中重复的数字
* Created by Elvis on 2019/12/31.
*/
public class S50 {
public static void main(String[] args) {
int[] numbers = new int[] {6,3,1,0,2,5,3};
int[] duplication = new int[1];
duplicate1(numbers, numbers.length, duplication);
System.out.println(duplication[0]);
}
public static boolean duplicate1(int numbers[],int length,int [] duplication) {
if (numbers == null || length < 2) return false;
for (int i = 0; i < length; i++) {
while (numbers[i] != i) {
if (numbers[i] == numbers[numbers[i]]) {
duplication[0] = numbers[i];
return true;
}
swap(numbers, i, numbers[i]);
}
}
return false;
}
public static void swap (int[] arr, int i, int j) {
if (i == j) return;
arr[i] ^= arr[j];
arr[j] ^= arr[i];
arr[i] ^= arr[j];
}
public static boolean duplicate(int numbers[],int length,int [] duplication) {
if (numbers == null || length < 2) return false;
Set<Integer> set = new HashSet<>();
for (int i = 0; i < length; i++) {
if (!set.contains(numbers[i])) {
set.add(numbers[i]);
} else {
duplication[0] = numbers[i];
return true;
}
}
return false;
}
}