分治法——快速排序
步驟:
![](https://img.laitimes.com/img/__Qf2AjLwojIjJCLyojI0JCLiAzNfRHLGZkRGZkRfJ3bs92YsYTMfVmepNHL4tGVPJTQ61UMRpHW3BjMMBjVtJWd0ckW65UbM5WOHJWa5kHT20ESjBjUIF2X0hXZ0xCMx81dvRWYoNHLrdEZwZ1Rh5WNXp1bwNjW1ZUba9VZwlHdssmch1mclRXY39CXldWYtlWPzNXZj9mcw1ycz9WL49zZuBnLxAjN3ITOyUTMxIjMxAjMwIzLc52YucWbp5GZzNmLn9Gbi1yZtl2Lc9CX6MHc0RHaiojIsJye.png)
例子
程式代碼
package ch01;
public class qSort {
public static void quickSort(int[] arr,int low,int high){
int i,j,temp,t;
if(low>high){
return;
}
i=low;
j=high;
//temp就是基準位
temp = arr[low];
while (i<j) {
//先看右邊,依次往左遞減
while (temp<=arr[j]&&i<j) {
j--;
}
//再看左邊,依次往右遞增
while (temp>=arr[i]&&i<j) {
i++;
}
//如果滿足條件則交換
if (i<j) {
t = arr[j];
arr[j] = arr[i];
arr[i] = t;
}
}
//最後将基準為與i和j相等位置的數字交換
arr[low] = arr[i];
arr[i] = temp;
//遞歸調用左半數組
quickSort(arr, low, j-1);
//遞歸調用右半數組
quickSort(arr, j+1, high);
}
public static void main(String[] args){
int[] arr = {10,7,2,4,7,62,3,4,2,1,8,9,19};
quickSort(arr, 0, arr.length-1);
for (int i = 0; i < arr.length; i++) {
System.out.print(arr[i]+" ");
}
}
}