[英]Removing elements from 2 ArrayList in java inside 2 for loops
有N個男孩和N個女孩。 只有一個男孩和一個女孩可以組成跳舞對(即,不允許同性跳舞對)。 成對時的唯一其他條件是它們的絕對高度差應小於或等於K。
找到可以形成的最大對數,以便每個人都有唯一的伙伴。
輸入格式第一行將包含兩個整數N和K。第二行將包含N個整數,N個男孩的高度。 第三行將包含N個整數,即N個女孩的高度。
約束1≤N≤1051≤K≤1091≤男孩或女孩的身高≤109
輸出格式包含最大可能對數的一行。
我的問題是在滿足條件后從拖曳數組中刪除元素。 (存儲兩個數組后)
我使用的第一個算法:
Arrays.sort(ArrBoys);
Arrays.sort(ArrGirls);
double count = 0;
for (int i = 0; i < ArrGirls.length; i++) {
for (int j = 0; j < ArrBoys.length; j++) {
if ((int) Math.abs(ArrBoys[j] - ArrGirls[i]) <= k) {
ArrBoys[j] = 0;
ArrGirls[i] = 0;
count++;
break;
}
}
}
System.out.println((int) count);
這絕對是錯誤的,因為我們需要刪除該元素而不是使其為零,所以我意識到我需要將它們轉換為ArrayLists。 然后我來了這個代碼:
double count = 0;
int dif = 0;
for (Integer ArrGirl : ArrGirls) {
loop1:
{
for (Integer ArrBoy : ArrBoys) {
dif = (int) Math.abs(ArrBoy - ArrGirl);
if (dif <= k) {
System.out.println("we took " + ArrBoy + " from boys with "
+ ArrGirl + " from girls, thier dif is " + dif);
ArrBoys.remove(ArrBoy);
ArrGirls.remove(ArrGirl);
count++;
break loop1;
}
}
}
}
System.out.println((int) count);
使用這種算法給我這樣的異常:
Exception in thread "main" java.util.ConcurrentModificationException at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901) at java.util.ArrayList$Itr.next(ArrayList.java:851)
在我搜索了此異常之后,我發現我應該在使用remove方法時使用Iterator,然后我使用了以下代碼:
double count = 0;
int dif = 0;
Iterator<Integer> iteB = ArrGirls.iterator();
Iterator<Integer> iteG = ArrGirls.iterator();
while (iteG.hasNext()) {
int value2 = iteG.next();
while (iteB.hasNext()) {
int value = iteB.next();
dif = (int) Math.abs(value - value2);
if (dif <= k) {
System.out.println("we took " + value + " from boys with " + value2
+ " from girls, thier dif is " + dif);
count++;
iteB.remove();
iteG.remove();
}
}
}
System.out.println((int) count);
這段代碼給了我錯誤的信息,也給了我同樣的異常。
這是我第一次使用ArrayList,您是否有任何糾正此代碼的想法?
您每次都必須為女孩重新分配迭代器。
int k = 5;
int count = 0;
ArrayList<Integer> ArrGirls = new ArrayList<>((List<Integer>) Arrays.asList(new Integer[]{34, 37, 28, 16, 44, 36, 37, 43, 50, 22}));
ArrayList<Integer> ArrBoys = new ArrayList<>((List<Integer>) Arrays.asList(new Integer[]{13, 28, 41, 10, 14, 27, 41, 27, 23, 37}));
for (Iterator<Integer> iteG = ArrGirls.iterator(); iteG.hasNext();) {
{
Integer ArrGirl = iteG.next();
for (Iterator<Integer> iteB = ArrBoys.iterator(); iteB.hasNext();) {
Integer ArrBoy = iteB.next();
int dif = (int) Math.abs(ArrBoy - ArrGirl);
if (dif <= k) {
System.out.println("we took " + ArrBoy + " from boys with "
+ ArrGirl + " from girls, thier dif is " + dif);
ArrBoys.remove(ArrBoy);
ArrGirls.remove(ArrGirl);
iteG = ArrGirls.iterator();//You have to reset the value of iterationGirls
count++;
break;
}
}
}
}
System.out.println(count);
// This helps I guess with little modifications for taking the inputs
public class Boy {
private int height;
public int getHeight() {
return height;
}
public void setHeight(int height) {
this.height = height;
}
}
public class Girl {
private int height;
public int getHeight() {
return height;
}
public void setHeight(int height) {
this.height = height;
}
}
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
public class Program {
public static void main(String[] args) {
int k=11;
Random random = new Random();
List<Boy> boys = new ArrayList<Boy>();
List<Girl> girls = new ArrayList<Girl>();
int noOfcombinations = 0;
for(int i=1;i<=100;i++)
{
Boy boy = new Boy();
boy.setHeight(random.nextInt(109));
Girl girl = new Girl();
girl.setHeight(random.nextInt(109));
boys.add(boy);
girls.add(girl);
}
for (Boy boy : boys) {
for (Girl girl : girls) {
if(Math.abs(boy.getHeight()-girl.getHeight())<k)
{
noOfcombinations++;
}
}
}
System.out.println("No of combinations is "+noOfcombinations);
}
}
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