4. Basis（待补充分治，动态规划，贪心，回溯，分支界限）
Java Version： jdk1.8
冒泡排序BubbleSort
package cn.chendongfang.algorithm.sort;
import java.util.Arrays;
public class BubbleSort {
public int[] sort(int[] sourceArray) throws Exception {
int[] arr = Arrays.copyOf(sourceArray, sourceArray.length);
for (int i = 1; i < arr.length; i++) {
boolean flag = true;
for (int j = 0; j < arr.length - i; j++) {
if (arr[j] > arr[j + 1]) {
swap(arr[j],arr[j + 1]);
flag = false;
}
}
if (flag) {
break;
}
}
return arr;
}
private void swap(int a,int b){
int tmp = a;
a = b;
b = tmp;
}
}
选择排序SelectionSort
package cn.chendongfang.algorithm.sort;
import java.util.Arrays;
public class SelectionSort {
public int[] sort(int[] sourceArray) throws Exception {
int[] arr = Arrays.copyOf(sourceArray, sourceArray.length);
for (int i = 0; i < arr.length - 1; i++) {
int min = i;
for (int j = i + 1; j < arr.length; j++) {
if (arr[j] < arr[min]) {
min = j;
}
}
if (i != min) {
swap(arr[i] ,arr[min]);
}
}
return arr;
}
private void swap(int a, int b) {
int tmp = a;
a = b;
b = tmp;
}
}
插入排序InsertSort
package cn.chendongfang.algorithm.sort;
import java.util.Arrays;
public class InsertSort {
public int[] sort(int[] sourceArray) throws Exception {
int[] arr = Arrays.copyOf(sourceArray, sourceArray.length);
for (int i = 1; i < arr.length; i++) {
int tmp = arr[i];
int j = i;
while (j > 0 && tmp < arr[j - 1]) {
arr[j] = arr[j - 1];
j--;
}
if (j != i) {
arr[j] = tmp;
}
}
return arr;
}
}
希尔排序ShellSort
package cn.chendongfang.algorithm.sort;
import java.util.Arrays;
public class ShellSort {
public static void shellSort(int[] sourceArray) {
int[] arr = Arrays.copyOf(sourceArray, sourceArray.length);
int length = arr.length;
int temp;
for (int step = length / 2; step >= 1; step /= 2) {
for (int i = step; i < length; i++) {
temp = arr[i];
int j = i - step;
while (j >= 0 && arr[j] > temp) {
arr[j + step] = arr[j];
j -= step;
}
arr[j + step] = temp;
}
}
}
}
归并排序MergeSort
package cn.chendongfang.algorithm.sort;
import java.util.Arrays;
public class MergeSort {
public int[] sort(int[] sourceArray) throws Exception {
int[] arr = Arrays.copyOf(sourceArray, sourceArray.length);
if (arr.length < 2) {
return arr;
}
int middle = (int) Math.floor(arr.length / 2);
int[] left = Arrays.copyOfRange(arr, 0, middle);
int[] right = Arrays.copyOfRange(arr, middle, arr.length);
return merge(sort(left), sort(right));
}
protected int[] merge(int[] left, int[] right) {
int[] result = new int[left.length + right.length];
int i = 0;
while (left.length > 0 && right.length > 0) {
if (left[0] <= right[0]) {
result[i++] = left[0];
left = Arrays.copyOfRange(left, 1, left.length);
} else {
result[i++] = right[0];
right = Arrays.copyOfRange(right, 1, right.length);
}
}
while (left.length > 0) {
result[i++] = left[0];
left = Arrays.copyOfRange(left, 1, left.length);
}
while (right.length > 0) {
result[i++] = right[0];
right = Arrays.copyOfRange(right, 1, right.length);
}
return result;
}
}
快速排序QuickSort
package cn.chendongfang.algorithm.sort;
import java.util.Arrays;
public class QuickSort {
public int[] sort(int[] sourceArray) throws Exception {
int[] arr = Arrays.copyOf(sourceArray, sourceArray.length);
return quickSort(arr, 0, arr.length - 1);
}
private int[] quickSort(int[] arr, int left, int right) {
if (left < right) {
int partitionIndex = partition(arr, left, right);
quickSort(arr, left, partitionIndex - 1);
quickSort(arr, partitionIndex + 1, right);
}
return arr;
}
private int partition(int[] arr, int left, int right) {
int pivot = left;
int index = pivot + 1;
for (int i = index; i <= right; i++) {
if (arr[i] < arr[pivot]) {
swap(arr, i, index);
index++;
}
}
swap(arr, pivot, index - 1);
return index - 1;
}
private void swap(int[] arr, int i, int j) {
int temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
}
堆排序HeapSort
package cn.chendongfang.algorithm.sort;
import java.util.Arrays;
public class HeapSort {
public int[] sort(int[] sourceArray) throws Exception {
int[] arr = Arrays.copyOf(sourceArray, sourceArray.length);
int len = arr.length;
buildMaxHeap(arr, len);
for (int i = len - 1; i > 0; i--) {
swap(arr, 0, i);
len--;
heapify(arr, 0, len);
}
return arr;
}
private void buildMaxHeap(int[] arr, int len) {
for (int i = (int) Math.floor(len / 2); i >= 0; i--) {
heapify(arr, i, len);
}
}
private void heapify(int[] arr, int i, int len) {
int left = 2 * i + 1;
int right = 2 * i + 2;
int largest = i;
if (left < len && arr[left] > arr[largest]) {
largest = left;
}
if (right < len && arr[right] > arr[largest]) {
largest = right;
}
if (largest != i) {
swap(arr, i, largest);
heapify(arr, largest, len);
}
}
private void swap(int[] arr, int i, int j) {
int temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
}
计数排序CountingSort
package cn.chendongfang.algorithm.sort;
import java.util.Arrays;
public class CountingSort {
public int[] sort(int[] sourceArray) throws Exception {
int[] arr = Arrays.copyOf(sourceArray, sourceArray.length);
int maxValue = getMaxValue(arr);
return countingSort(arr, maxValue);
}
private int[] countingSort(int[] arr, int maxValue) {
int bucketLen = maxValue + 1;
int[] bucket = new int[bucketLen];
for (int value : arr) {
bucket[value]++;
}
int sortedIndex = 0;
for (int j = 0; j < bucketLen; j++) {
while (bucket[j] > 0) {
arr[sortedIndex++] = j;
bucket[j]--;
}
}
return arr;
}
private int getMaxValue(int[] arr) {
int maxValue = arr[0];
for (int value : arr) {
if (maxValue < value) {
maxValue = value;
}
}
return maxValue;
}
}
桶排序BucketSort
package cn.chendongfang.algorithm.sort;
import java.util.Arrays;
public class BucketSort {
public int[] sort(int[] sourceArray) throws Exception {
int[] arr = Arrays.copyOf(sourceArray, sourceArray.length);
return bucketSort(arr, 5);
}
private int[] bucketSort(int[] arr, int bucketSize) throws Exception {
if (arr.length == 0) {
return arr;
}
int minValue = arr[0];
int maxValue = arr[0];
for (int value : arr) {
if (value < minValue) {
minValue = value;
} else if (value > maxValue) {
maxValue = value;
}
}
int bucketCount = (int) Math.floor((maxValue - minValue) / bucketSize) + 1;
int[][] buckets = new int[bucketCount][0];
for (int i = 0; i < arr.length; i++) {
int index = (int) Math.floor((arr[i] - minValue) / bucketSize);
buckets[index] = arrAppend(buckets[index], arr[i]);
}
int arrIndex = 0;
for (int[] bucket : buckets) {
if (bucket.length <= 0) {
continue;
}
sort(bucket);
for (int value : bucket) {
arr[arrIndex++] = value;
}
}
return arr;
}
private int[] arrAppend(int[] arr, int value) {
arr = Arrays.copyOf(arr, arr.length + 1);
arr[arr.length - 1] = value;
return arr;
}
}
基数排序RadixSort
package cn.chendongfang.algorithm.sort;
import java.util.Arrays;
public class RadixSort{
public int[] sort(int[] sourceArray) throws Exception {
int[] arr = Arrays.copyOf(sourceArray, sourceArray.length);
int maxDigit = getMaxDigit(arr);
return radixSort(arr, maxDigit);
}
private int getMaxDigit(int[] arr) {
int maxValue = getMaxValue(arr);
return getNumLenght(maxValue);
}
private int getMaxValue(int[] arr) {
int maxValue = arr[0];
for (int value : arr) {
if (maxValue < value) {
maxValue = value;
}
}
return maxValue;
}
protected int getNumLenght(long num) {
if (num == 0) {
return 1;
}
int lenght = 0;
for (long temp = num; temp != 0; temp /= 10) {
lenght++;
}
return lenght;
}
private int[] radixSort(int[] arr, int maxDigit) {
int mod = 10;
int dev = 1;
for (int i = 0; i < maxDigit; i++, dev *= 10, mod *= 10) {
int[][] counter = new int[mod * 2][0];
for (int j = 0; j < arr.length; j++) {
int bucket = ((arr[j] % mod) / dev) + mod;
counter[bucket] = arrayAppend(counter[bucket], arr[j]);
}
int pos = 0;
for (int[] bucket : counter) {
for (int value : bucket) {
arr[pos++] = value;
}
}
}
return arr;
}
private int[] arrayAppend(int[] arr, int value) {
arr = Arrays.copyOf(arr, arr.length + 1);
arr[arr.length - 1] = value;
return arr;
}
}
顺序查找BasicSearch
package cn.chendongfang.algorithm.search;
public class BasicSearch{
public int search(int[] arr, int number){
for (int i = 0; i < arr.length; i++) {
if(arr[i] == number){
return i;
}
}
return -1;
}
}
二分查找BinarySearch
package cn.chendongfang.algorithm.search;
public class BinarySearch {
public int binarySearch(int[] arr, int number){
//1.定义两个变量记录要查找的范围
int min = 0;
int max = arr.length - 1;
//2.利用循环不断的去找要查找的数据
while(true){
if(min > max){
return -1;
}
//3.找到min和max的中间位置
int mid = (min + max) / 2;
//4.拿着mid指向的元素跟要查找的元素进行比较
if(arr[mid] > number){
//4.1 number在mid的左边
//min不变，max = mid - 1；
max = mid - 1;
}else if(arr[mid] < number){
//4.2 number在mid的右边
//max不变，min = mid + 1;
min = mid + 1;
}else{
//4.3 number跟mid指向的元素一样
//找到了
return mid;
}
}
}
}
菜鸟教程
https://www.runoob.com/w3cnote/ten-sorting-algorithm.html
查找算法
https://blog.csdn.net/weixin_38189581/article/details/128199173