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Code03_PartitionAndQuickSort.java
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230 lines (208 loc) · 4.87 KB
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package class08;
import java.util.Stack;
public class Code03_PartitionAndQuickSort {
public static void splitNum1(int[] arr) {
int lessEqualR = -1;
int index = 0;
int N = arr.length;
while (index < N) {
if (arr[index] <= arr[N - 1]) {
swap(arr, ++lessEqualR, index++);
} else {
index++;
}
}
}
public static void splitNum2(int[] arr) {
int N = arr.length;
int lessR = -1;
int moreL = N - 1;
int index = 0;
// arr[N-1]
while (index < moreL) {
if (arr[index] < arr[N - 1]) {
swap(arr, ++lessR, index++);
} else if (arr[index] > arr[N - 1]) {
swap(arr, --moreL, index);
} else {
index++;
}
}
swap(arr, moreL, N - 1);
}
public static void swap(int[] arr, int i, int j) {
int tmp = arr[i];
arr[i] = arr[j];
arr[j] = tmp;
}
// arr[L...R]范围上，拿arr[R]做划分值，
// L....R < = >
public static int[] partition(int[] arr, int L, int R) {
int lessR = L - 1;
int moreL = R;
int index = L;
while (index < moreL) {
if (arr[index] < arr[R]) {
swap(arr, ++lessR, index++);
} else if (arr[index] > arr[R]) {
swap(arr, --moreL, index);
} else {
index++;
}
}
swap(arr, moreL, R);
return new int[] { lessR + 1, moreL };
}
public static void quickSort1(int[] arr) {
if (arr == null || arr.length < 2) {
return;
}
process(arr, 0, arr.length - 1);
}
public static void process(int[] arr, int L, int R) {
if (L >= R) {
return;
}
int[] equalE = partition(arr, L, R);
process(arr, L, equalE[0] - 1);
process(arr, equalE[1] + 1, R);
}
public static class Job {
public int L;
public int R;
public Job(int left, int right) {
L = left;
R = right;
}
}
public static void quickSort2(int[] arr) {
if (arr == null || arr.length < 2) {
return;
}
Stack<Job> stack = new Stack<>();
stack.push(new Job(0, arr.length - 1));
while (!stack.isEmpty()) {
Job cur = stack.pop();
int[] equals = partition(arr, cur.L, cur.R);
if (equals[0] > cur.L) { // 有< 区域
stack.push(new Job(cur.L, equals[0] - 1));
}
if (equals[1] < cur.R) { // 有 > 区域
stack.push(new Job(equals[1] + 1, cur.R));
}
}
}
public static int[] netherlandsFlag(int[] arr, int L, int R) {
if (L > R) {
return new int[] { -1, -1 };
}
if (L == R) {
return new int[] { L, R };
}
int less = L - 1;
int more = R;
int index = L;
while (index < more) {
if (arr[index] == arr[R]) {
index++;
} else if (arr[index] < arr[R]) {
swap(arr, index++, ++less);
} else {
swap(arr, index, --more);
}
}
swap(arr, more, R); // <[R] =[R] >[R]
return new int[] { less + 1, more };
}
public static void quickSort3(int[] arr) {
if (arr == null || arr.length < 2) {
return;
}
process3(arr, 0, arr.length - 1);
}
public static void process3(int[] arr, int L, int R) {
if (L >= R) {
return;
}
swap(arr, L + (int) (Math.random() * (R - L + 1)), R);
int[] equalArea = netherlandsFlag(arr, L, R);
process3(arr, L, equalArea[0] - 1);
process3(arr, equalArea[1] + 1, R);
}
// for test
public static int[] generateRandomArray(int maxSize, int maxValue) {
int[] arr = new int[(int) ((maxSize + 1) * Math.random())];
for (int i = 0; i < arr.length; i++) {
arr[i] = (int) ((maxValue + 1) * Math.random()) - (int) (maxValue * Math.random());
}
return arr;
}
// for test
public static int[] copyArray(int[] arr) {
if (arr == null) {
return null;
}
int[] res = new int[arr.length];
for (int i = 0; i < arr.length; i++) {
res[i] = arr[i];
}
return res;
}
// for test
public static boolean isEqual(int[] arr1, int[] arr2) {
if ((arr1 == null && arr2 != null) || (arr1 != null && arr2 == null)) {
return false;
}
if (arr1 == null && arr2 == null) {
return true;
}
if (arr1.length != arr2.length) {
return false;
}
for (int i = 0; i < arr1.length; i++) {
if (arr1[i] != arr2[i]) {
return false;
}
}
return true;
}
// for test
public static void printArray(int[] arr) {
if (arr == null) {
return;
}
for (int i = 0; i < arr.length; i++) {
System.out.print(arr[i] + " ");
}
System.out.println();
}
// for test
public static void main(String[] args) {
// int[] arr = { 7, 1, 3, 5, 4, 5, 1, 4, 2, 4, 2, 4 };
//
// splitNum2(arr);
// for (int i = 0; i < arr.length; i++) {
// System.out.print(arr[i] + " ");
// }
int testTime = 500000;
int maxSize = 100;
int maxValue = 100;
boolean succeed = true;
System.out.println("test begin");
for (int i = 0; i < testTime; i++) {
int[] arr1 = generateRandomArray(maxSize, maxValue);
int[] arr2 = copyArray(arr1);
int[] arr3 = copyArray(arr1);
quickSort1(arr1);
quickSort2(arr2);
quickSort3(arr3);
if (!isEqual(arr1, arr2) || !isEqual(arr1, arr3)) {
System.out.println("Oops!");
succeed = false;
break;
}
}
System.out.println("test end");
System.out.println(succeed ? "Nice!" : "Oops!");
}
}