java简单查找回顾

package jvm;public class Dichotomy {public static void main(String[] args) {int[] is = new int[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };System.out.println("循环：" + binarySearch(is, 4));System.out.println("迭代：" + binarySearch(is, 4, 0, is.length - 1));}/** * 二分法：顺序、循环 *  * @param data * @param i * @return */private static int binarySearch(int[] data, int i) {if (data == null || data.length <= 0) {return -1;}int low = 0;int high = data.length - 1;while (low <= high) {int mid = (low + high) / 2;if (data[mid] == i) {return mid;} else if (data[mid] < i) {low = mid + 1;} else if (data[mid] > i) {high = mid - 1;}}return -1;}private static int binarySearch(int[] data, int i, int low, int high) {if (data == null || data.length <= 0) {return -1;}if (low <= high) {int mid = (low + high) / 2;if (data[mid] == i) {return i;} else if (data[mid] < i) {binarySearch(data, i, mid + 1, high);} else if (data[mid] > i) {binarySearch(data, i, low, mid - 1);}}return i;}}

查找算法之哈希查找

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package jvm;public class HashSearch {public static void main(String[] args) {//“除法取余法”        int hashLength = 13;        int [] array  = { 13, 29, 27, 28, 26, 30, 38 };        //哈希表长度        int[] hash = new int[hashLength];        //创建hash        for (int i = 0; i < array.length; i++)        {            insertHash(hash, hashLength, array[i]);        }                int result = searchHash(hash,hashLength, 29);if (result != -1)System.out.println("已经在数组中找到，索引位置为：" + result);elseSystem.out.println("没有此原始");}/**** * Hash表检索数据 *  * @param hash * @param hashLength * @param key * @return */public static int searchHash(int[] hash, int hashLength, int key) {// 哈希函数int hashAddress = key % hashLength;// 指定hashAdrress对应值存在但不是关键值，则用开放寻址法解决while (hash[hashAddress] != 0 && hash[hashAddress] != key) {hashAddress = (++hashAddress) % hashLength;}// 查找到了开放单元，表示查找失败if (hash[hashAddress] == 0)return -1;return hashAddress;}/*** * 数据插入Hash表 *  * @param hash 哈希表 * @param hashLength * @param data */public static void insertHash(int[] hash, int hashLength, int data) {// 哈希函数int hashAddress = data % hashLength;// 如果key存在，则说明已经被别人占用，此时必须解决冲突while (hash[hashAddress] != 0) {// 用开放寻址法找到hashAddress = (++hashAddress) % hashLength;}// 将data存入字典中hash[hashAddress] = data;}}//运行结果：//已经在数组中找到，索引位置为：3