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[英]Sort Array by Alphabetical order using SelectionSort without Array.sort
[英]How to sort array in alphabetical order without using Array.sort:Java
我想在Java中按字母順序對數組的值進行排序。我再次查看數組並獲得輸出。 我的目的是:遍歷單詞數組,找到最大的字符串(按字典順序排列),找到它后,在sortedWords數組的末尾插入單詞,將sortedArray的索引向左移動一個位置,減少原始數組刪除已經找到的單詞,再次循環找到下一個單詞....
謝謝你的幫助。
以下是我到目前為止所做的工作。
公共類Main {
public static void main(String[] args) {
String[] words = {"bob","alice","keith","zoe","sarah","gary"};
String[] sortedWords = new String[words.length];
// Copy of the original array
for(int i = 0; i < sortedWords.length;i++){
sortedWords[i]= words[i];
}
for (int i = 0; i < words.length - 1; i++) {
int currentSize = words.length;
int position = 0;
boolean found = false;
while (position < currentSize && !found) {
if (words[i].equals(largestAlphabetically(words))) {
found = true;
} else {
position++;
}
}
if(found){
insertAtEnd(words,largestAlphabetically(words));
shiftLeft(sortedWords,i);
shorterArray(words);
}
}
for(int i = 0;i < sortedWords.length;i++){
System.out.println(sortedWords[i]);
}
}
/**
* This method inserts the largest string lexicographically at the end of the array
* @param words
* @param wordToInsert
* @return an array with string at the end
*/
public static String [] insertAtEnd(String[] words, String wordToInsert) {
for (int i = 0; i < words.length; i++) {
int currentSize = words.length - 1;
wordToInsert = largestAlphabetically(words);
if (currentSize < words.length) {
currentSize++;
words[currentSize - 1] = wordToInsert;
}
}
return words;
}
/**
* This method determines the largest string in an array
* @param words
* @return largest string lexicographically
*/
public static String largestAlphabetically(String[] words) {
String searchedValue = words[0];
for (int i = 0; i < words.length; i++) {
for (int j = 0; j < words.length; j++) {
if (words[i].compareToIgnoreCase(words[j]) < 0) {
searchedValue = words[j];
}
}
}
return searchedValue;
}
/**
* To shift the array index to the left
* @param dest
* @param from
*/
public static void shiftLeft(String[] dest, int from) {
for (int i = from + 1; i < dest.length; i++) {
dest[i - 1] = dest[i];
}
dest[dest.length - 1] = dest[0];
}
/**
* Remove the largest word from a string while maintaining the order of the array
* @param words
* @return return a shorter array
*/
public static String [] shorterArray(String[] words) {
String [] shorterArray = new String[words.length];
int currentSize = words.length;
String searchedValue = largestAlphabetically(words);
int position = 0;
boolean found = false;
while (position < currentSize && !found) {
if (words[position] == searchedValue) {
found = true;
} else {
position++;
}
}
if (found) {
for (int i = position + 1; i < currentSize; i++) {
words[i - 1] = words[i];
}
currentSize--;
shorterArray = words;
}
return shorterArray;
}
}
簡單的實現可以是這樣的:
String[] words = {"bob","alice","keith","zoe","sarah","gary"};
boolean isSwapped = false;
do {
isSwapped = false;
for(int i=0;i<words.length-1;i++){
if(words[i].compareTo(words[i+1])>0){
String temp = words[i+1];
words[i+1] = words[i];
words[i] = temp;
isSwapped = true;
}
}
}while((isSwapped));
我不知道為什么你不想使用Arrays.sort()或Collections.sort(),無論如何,如果你真的想要實現一個簡單的排序算法,你可以從插入排序開始,如一些評論中所建議的那樣。 這是一個簡單的實現:
String[] words = {"bob","alice","keith","zoe","sarah","gary"};
for(int i = 0; i < words.length; i++)
{
int smallest = i;
for(int j = i + 1; j < words.length; j++) // here you find the index of the minimum String between the strings in the unsorted side of the array
{
if(words[j].compareTo(words[i]) < 0)
smallest = j;
}
//put the new minimum in the i-th position.
String aux = words[i];
words[i] = words[smallest];
words[smallest] = aux;
}
for(int i = 0; i < words.length; i++)
{
System.out.println(words[i]);
}
請注意,這是就地排序,因此您不需要輔助數組。 希望很清楚
你可以像這樣比較兩個字符串:
"a".compareTo("b"); // returns a negative number, here -1
"a".compareTo("a"); // returns 0
"b".compareTo("a"); // returns a positive number, here 1
所以你可以寫一個小Blubblesort。 鏈接: https : //en.wikipedia.org/wiki/Bubble_sort
堆排序似乎是按字典順序對數組字符串進行排序的最佳方法。 二進制最大堆將是要走的路。 在Java中,它可以使用PriorityQueue實現。
我使用PriorityQueue的自編程接口編寫了BinaryMinHeap 。 你會在這里找到這個項目。 [請注意不要在沒有引用的情況下復制任何代碼。]
這是否回答你的問題?
//使用可以對任何類型的數據進行排序的通用算法。 //選擇排序
public class Selection {
static public void sort(Comparable...a){
int N = a.length;
for(int i=0;i<N;i++){
int min = i;
for(int j=i+1;j<N;j++){
if(less(a[j],a[min]))
min = j;
swap(a,i,min);
}
}
}
static private boolean less(Comparable a,Comparable b){
return a.compareTo(b)<0;//return true if a is a-b<0;meaning a is less than b
}
static private void swap(Comparable[] a,int i,int j){
Comparable temp = a[i];
a[i] = a[j];
a[j] = temp;
}
static public boolean isSorted(Comparable...a){
int N = a.length;
for(int i=1;i<N;i++){
if(less(a[i],a[i-1]))//if a[i]<a[i-1] then the array is not in order. Eg. a[1]=5,a[(1-1=0)]=6 then the isNotSorted
return false;
}
return true;
}
}
現在使用測試客戶端
public class MainClass{
String[] words = {"bob","alice","keith","zoe","sarah","gary"};
for(String word:words){System.out.println(e+" ");}//print the words before sorting
words.sort(words);
for(String word:words){System.out.println(e+" ");}//print the words after sorting
}
該算法可以對您想要的任何類型的數據進行排序。 例如。 String,Integer和實現Comparable的任何數據類型
public boolean isSorted(String[] a) {
for (int i = 0; i < a.length; i++) {
if (a[i - 1].compareTo(a[i]) > 0) {
return false;
}
}
return true;
}
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