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Copy pathSorting.java
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104 lines (96 loc) · 2.65 KB
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package sorting;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
public class Sorting {
public static List<Integer> bubbleSort(List<Integer> arr) {
int temp = 0;
for (int i = 0; i < arr.size() - 1; i++) {
for (int j = 0; j < arr.size() - 1; j++) {
if (arr.get(j) > arr.get(j + 1)) {
temp = arr.get(j);
arr.set(j, arr.get(j + 1));
arr.set(j + 1, temp);
}
}
}
return arr;
}
public static List<Integer> selectionSort(List<Integer> arr) {
for (int i = 0; i < arr.size() - 1; i++) {
int min = arr.get(i);
int index = i;
for (int j = i + 1; j < arr.size(); j++) {
if (min > arr.get(j)) {
min = arr.get(j);
index = j;
}
}
arr.set(index, arr.get(i));
arr.set(i, min);
}
return arr;
}
public static List<Integer> quickSort(List<Integer> arr) {
if (arr.size() < 2) {
return arr;
}
int pivot = arr.get(0);
List<Integer> less = new ArrayList<>();
List<Integer> middle = new ArrayList<>(); // 엄청 중요하다 ! 중복 원소 예외 처리 !
List<Integer> greater = new ArrayList<>();
for (int element : arr) {
if (element < pivot) {
less.add(element);
}
if (element > pivot) {
greater.add(element);
}
if (element == pivot) {
middle.add(element);
}
}
List<Integer> newArr = new ArrayList<>();
newArr.addAll(quickSort(less));
newArr.addAll(middle);
newArr.addAll(quickSort(greater));
return newArr;
}
// divide conquer로 sum 만들기
public static int sumByDivideConqur(int[] arr) {
if (arr.length == 0) {
return 0;
}
if (arr.length <= 1) {
return arr[0];
}
int midIndex = arr.length / 2;
int[] less = new int[midIndex];
int[] greater = new int[arr.length - midIndex];
for (int i = 0; i < midIndex; i++) {
less[i] = arr[i];
}
for (int i = 0; i < arr.length - midIndex; i++) {
greater[i] = arr[midIndex + i];
}
return sumByDivideConqur(less) + sumByDivideConqur(greater);
}
public static void main(String[] args) {
List<Integer> arrList = Arrays.asList(1,10,3,0,0,0,0,15,-1,10,9);
int[] arr = new int[10000];
for (int i = 0; i < arr.length; i++) {
arr[i] = i + 1;
}
System.out.println(Collections.max(arrList));
// System.out.println(arrList);
// List<Integer> newArrList = new ArrayList<>();
// System.out.println(sumByDivideConqur(arr));
// newArrList = quickSort(arrList);
// System.out.println(quickSort(newArrList));
// System.out.println(bubbleSort(arrList));
// System.out.println(selectionSort(arrList));
// System.out.println(Collections.max(arrList)); // 최대값
// System.out.println(Collections.min(arrList)); // 최소값
}
}