冒泡排序和快速排序的java实现

public static int[] bubble_sort(int[] arr) {
int n = arr.length;
for (int i = 0; i < n - 1; i++) {//每次循环代表一轮冒泡，一轮冒泡后顶端的数字一定是最大的
for (int j = 0; j < n - 1 - i; j++) {
if (arr[j] < (arr[j + 1])) {
int tmp = arr[j + 1];
arr[j + 1] = arr[j];
arr[j] = tmp;
}

}
}

return arr;

}

public static void quick_sort(int[] arr, int start, int end) {

if (start >= end) {
// System.out.println("qs finish");
return;
}
int x = arr[start];
int s = start;
int e = end;

while (s < e) {
if (arr[e] < x) {
for (; s < e; s++) {
if (arr[s] > x) {
int tmp = arr[s];
arr[s] = arr[e];
arr[e] = tmp;
// System.out.println("switch " + arr[s] + " " +
// arr[e]);
// System.out.println("s is " + s + " e is " + e);
break;
}
}
} else {
e--;

}
}
// System.out.println(" the end s is " + s + " e is " + e +
// " arr[s] is "
// + arr[s]+"  arr[start] is "+arr[start]);

arr[start] = arr[s];

arr[s] = x;

System.out.println("quick_sort is "+Arrays.toString(arr));

quick_sort(arr, start, s - 1);
quick_sort(arr, s + 1, end);

}

public static void quick_sort2(int[] arr, int start, int end) {

if (start < end) {

int x = arr[start];
int s = start;
int e = end;

while (s < e) { //退出循环代表一轮排序结束，首尾游标相遇
while (s < e && (arr[e] >= x)) // 从右向左找第一个小于x的数
{
e--;
}

while (s < e && (arr[s] <= x)) // 从右向左找第一个小于x的数
{
s++;
}

if (s < e) {// 左右两个数交换
int tmp = arr[s];
arr[s] = arr[e];
arr[e] = tmp;

//                    System.out.println("switch " + arr[s] + " " + arr[e]);
//                    System.out.println("s is " + s + " e is " + e);
}

}

arr[start] = arr[s]; //基准数归位到数组中正确位置

arr[s] = x;

System.out.println("quick_sort2 is "+Arrays.toString(arr));

quick_sort2(arr, start, s - 1);
quick_sort2(arr, s + 1, end);

}

}