正文
java 选择排序、冒泡排序、折半查找
小程序：扫一扫查出行【扫一扫了解最新限行尾号】
复制小程序
public class SortAndSelectDemo{
public static void main(String[] args){
int[] arr = {3, 5, 17, 2, 11, 13, 19, 7, 23};
//bubbleSort(arr);
selectSort(arr);
printArr(arr);
int searchIndex = halfSearch(arr,6);
System.out.println(searchIndex);
}
//选择排序
public static void selectSort(int[] arr){
for(int i = 0; i < arr.length-1; i++){
for(int j = i+1; j < arr.length-1; j++){
if(arr[i] > arr[j]){
int temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
}
}
}
//冒泡排序
//外循环：对比n-1次，内循环：n-1次随i递减
public static void bubbleSort(int[] arr){
for(int i = 0; i < arr.length-1; i++){
for(int j = 0; j < arr.length-1-i; j++){
if(arr[j] > arr[j+1]){
int temp = arr[j];
arr[j] = arr[j+1];
arr[j+1] = temp;
}
}
}
}
//折半查找
public static int halfSearch(int[] arr, int searchNum){
int minIndex = 0;
int maxIndex = arr.length;
int midIndex = 0;
while(minIndex < maxIndex){
midIndex = (minIndex + maxIndex)/2;
if(arr[midIndex] > searchNum){
maxIndex = midIndex-1;
}else if(arr[midIndex] < searchNum){
minIndex = midIndex + 1;
}else{
return midIndex;
}
}
return -1;
}
public static void printArr(int[] arr){
System.out.print("[");
for(int i = 0;i < arr.length; i++){
if(i == arr.length-1){
System.out.println(arr[i] + "]");
}else{
System.out.print(arr[i] + "\t");
}
}
}
}
选择排序：
冒泡排序：
