如何在Java中使用函数来排序和搜索数组?
发布时间:2023-09-16 00:50:38
在Java中,可以使用函数来排序和搜索数组。排序可以使用不同的算法,如冒泡排序、选择排序、插入排序、快速排序、归并排序等。搜索可以使用线性搜索、二分搜索等方法。以下是使用函数在Java中进行数组排序和搜索的示例代码:
1. 冒泡排序:
public static void bubbleSort(int[] arr) {
int n = arr.length;
for (int i = 0; i < n-1; i++) {
for (int j = 0; j < n-i-1; j++) {
if (arr[j] > arr[j+1]) {
int temp = arr[j];
arr[j] = arr[j+1];
arr[j+1] = temp;
}
}
}
}
2. 选择排序:
public static void selectionSort(int[] arr) {
int n = arr.length;
for (int i = 0; i < n-1; i++) {
int minIdx = i;
for (int j = i+1; j < n; j++) {
if (arr[j] < arr[minIdx]) {
minIdx = j;
}
}
int temp = arr[minIdx];
arr[minIdx] = arr[i];
arr[i] = temp;
}
}
3. 插入排序:
public static void insertionSort(int[] arr) {
int n = arr.length;
for (int i = 1; i < n; i++) {
int key = arr[i];
int j = i - 1;
while (j >= 0 && arr[j] > key) {
arr[j+1] = arr[j];
j--;
}
arr[j+1] = key;
}
}
4. 快速排序:
public static void quickSort(int[] arr, int low, int high) {
if (low < high) {
int pi = partition(arr, low, high);
quickSort(arr, low, pi-1);
quickSort(arr, pi+1, high);
}
}
private static int partition(int[] arr, int low, int high) {
int pivot = arr[high];
int i = low - 1;
for (int j = low; j < high; j++) {
if (arr[j] < pivot) {
i++;
int temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
}
int temp = arr[i+1];
arr[i+1] = arr[high];
arr[high] = temp;
return i+1;
}
5. 归并排序:
public static void mergeSort(int[] arr, int left, int right) {
if (left < right) {
int mid = (left + right) / 2;
mergeSort(arr, left, mid);
mergeSort(arr, mid+1, right);
merge(arr, left, mid, right);
}
}
private static void merge(int[] arr, int left, int mid, int right) {
int n1 = mid - left + 1;
int n2 = right - mid;
int[] L = new int[n1];
int[] R = new int[n2];
for (int i = 0; i < n1; i++) {
L[i] = arr[left + i];
}
for (int j = 0; j < n2; j++) {
R[j] = arr[mid + 1 + j];
}
int i = 0, j = 0;
int k = left;
while (i < n1 && j < n2) {
if (L[i] <= R[j]) {
arr[k] = L[i];
i++;
} else {
arr[k] = R[j];
j++;
}
k++;
}
while (i < n1) {
arr[k] = L[i];
i++;
k++;
}
while (j < n2) {
arr[k] = R[j];
j++;
k++;
}
}
6. 线性搜索:
public static int linearSearch(int[] arr, int target) {
for (int i = 0; i < arr.length; i++) {
if (arr[i] == target) {
return i;
}
}
return -1;
}
7. 二分搜索:
public static int binarySearch(int[] arr, int target) {
int left = 0, right = arr.length - 1;
while (left <= right) {
int mid = left + (right - left) / 2;
if (arr[mid] == target) {
return mid;
}
if (arr[mid] < target) {
left = mid + 1;
} else {
right = mid - 1;
}
}
return -1;
}
以上是一些常用的排序和搜索算法的示例代码。在实际应用中,可以根据具体需求选择合适的算法进行排序和搜索。
