مساله:
آرایه ای از نوع int به شما داده می شود، شما باید عددی را که در آن به صورت فرد تکرار شده است را پیدا کنید:
همیشه فقط یک عدد فرد در لیست وجود دارد.
Description:
Given an array of integers, find the one that appears an odd number of times.
There will always be only one integer that appears an odd number of times.
Examples
[7] should return 7, because it occurs 1 time (which is odd).
[0] should return 0, because it occurs 1 time (which is odd).
[1,1,2] should return 2, because it occurs 1 time (which is odd).
[0,1,0,1,0] should return 0, because it occurs 3 times (which is odd).
[1,2,2,3,3,3,4,3,3,3,2,2,1] should return 4, because it appears 1 time (which is odd).
public class FindOdd {
public static int findIt(int[] A) {
int xor = 0;
for (int i = 0; i < A.length; i++) {
xor ^= A[i];
}
return xor;
}
}import static java.util.Arrays.stream;
public class FindOdd {
public static int findIt(int[] arr) {
return stream(arr).reduce(0, (x, y) -> x ^ y);
}
}public class FindOdd {
public static int findIt(int[] A) {
int odd=0;
for (int item: A)
{
odd = odd ^ item;// XOR will cancel out everytime you XOR with the same number so 1^1=0 but 1^1^1=1 so every pair should cancel out leaving the odd number out
}
return odd;
}
}import java.util.HashMap;
import java.util.Map;
public class FindOdd {
public static int findIt(int[] a) {
Map<Integer, Integer> counts = new HashMap<>(a.length);
for(int i : a) {
if(!counts.containsKey(i)) counts.put(i, 1);
else counts.put(i, counts.get(i) + 1);
}
for(Map.Entry<Integer, Integer> entry : counts.entrySet()) if(entry.getValue() % 2 == 1) return entry.getKey();
return 0;
}
}public class FindOdd {
public static int findIt(int[] A) {
int odd = 0;
for (int i : A) {
odd ^= i;
}
return odd;
}
}import java.util.ArrayList;
import java.util.Arrays;
import java.util.Map;
import java.util.function.Function;
import java.util.stream.Collectors;
import org.apache.commons.lang3.ArrayUtils;
public class FindOdd {
public static int findIt(int[] a) {
Map<Integer, Long> map = Arrays.asList(ArrayUtils.toObject(a))
.stream().collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));
return new ArrayList<>(map.keySet()).stream().filter(x -> map.get(x)%2==1).collect(Collectors.toList()).get(0).intValue();
}
}
