[英]Compare elements in an array for duplicates
I am trying to generate a 5 digit int
array in Java and am having trouble on where to start. 我试图在Java中生成一个5位数的int
数组,并且无法从哪里开始。 None of the numbers in the array can be duplicates. 数组中的数字都不能重复。 I can generate random numbers for it fine but just cant figure out how to compare the numbers to each other and replace any duplicates. 我可以为它生成随机数,但是无法弄清楚如何将数字相互比较并替换任何重复项。
您可以使用java.util.Set而不是数组,因为它保证只有唯一元素。
If I understand you correctly, you want a random 5 digit number, with no digit repeated? 如果我理解正确,你想要一个随机的5位数字,没有数字重复?
If so, one way is to shuffle a list of the digits 0-9, then pick the first 5 elements. 如果是这样,一种方法是将数字列表0-9混洗,然后选择前5个元素。
EDIT 编辑
Integer[] digits = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
Random random = new Random();
public Integer[] generateId() {
List<Integer> id = Arrays.asList(digits);
Collections.shuffle(id, random);
return id.subList(0, 5).toArray(new Integer[0]);
}
You can get rid of the duplicates by converting the array into a TreeSet (that will also sort them): 您可以通过将数组转换为TreeSet(也将对它们进行排序)来删除重复项:
int numbers[] { 4 5 7 6 5 7 5 89 847 7 94 093 02 10 11 10 11 };
TreeSet set new TreeSet(Arrays.asList(numbers));
for (int no : set)
System.out.println(no);
this generates it in O(number of digits), no inner loops, no shuffling <- this could be expensive if the number of choices gets really big 这会产生O(数字位数),没有内部循环,没有洗牌< - 如果选择的数量变得非常大,这可能会很昂贵
int[] digits = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
Random random = new Random();
int[] generateId() {
int[] choices = digits.clone();
int[] id = new int[5];
for (int i = 0; i < 5; i++) {
// one less choice to choose from each time
int index = random.nextInt(choices.length - i);
id[i] = choices[index];
// "remove" used item by replacing it with item at end of range
// because that index at the end won't be considered in next round
choices[index] = choices[choices.length - i - 1];
}
return id;
}
try this: 试试这个:
int[] digits = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
Random random = new Random();
int[] generateId() {
int[] clone = digits.clone();
int[] id = new int[5];
for (int i = 0; i < 5; i++) {
int candidate;
do {
candidate = random.nextInt(10);
} while (clone[candidate] == -1);
id[i] = clone[candidate];
clone[candidate] = -1;
}
return id;
}
As an alternative, just sort the array and iterate it. 作为替代方案,只需对数组进行排序并迭代它。
List<int> myList = new List<int>() { 1, 1, 2, 3, 4, 5, 5, 7 , 1, 7};
myList.Sort();
for (int i = myList.Count - 1; i > 0; i--)
{
if (myList[i] == myList[i - 1])
myList.RemoveAt(i);
}
But of course it's best not to get any duplicates to start with. 但当然最好不要重复开始。
First off i want to thank all of you for helping out i really appreciate it. 首先,我要感谢大家的帮助,我真的很感激。
I got this program to work the way i want but it seems like there should be an easier way though. 我得到了这个程序以我想要的方式工作,但似乎应该有一个更简单的方法。 Here is what i did. 这就是我做的。 Any more comments would be awesome. 任何更多的评论都会很棒。
do
{
for (int i = 0; i < 5; i++)
{
iNumber = generator.nextInt(9) + 1;
numbers[i] = iNumber;
}
}
while(numbers[0] == numbers[1] || numbers[0] == numbers[2] || numbers[0] == numbers[3] || numbers[0] == numbers[4] || numbers[1] == numbers[2] || numbers[1] == numbers[3] || numbers[1] == numbers[4] || numbers[2] == numbers[3] || numbers[2] == numbers[4] || numbers[3] == numbers[4]);
/**
* findDuplicate method return map where key is unique no and value as the
* repitation
*
* @param a
* : arrays of Objects
* @return map
*/
public Map findDuplicate(T[] a) {
Map<T, Integer> map = new HashMap<T, Integer>();
Set<T> unique = new HashSet<T>(Arrays.asList(a));
int count = 0;
for (T integer : unique) {
for (T integer1 : a) {
if (integer == integer1) {
++count;
}
}
map.put(integer, count);
count = 0;
}
return map;
}
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