hello-algo/codes/java/chapter_searching/hashing_search.java
2022-11-20 02:03:26 +08:00

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package chapter_searching;
import include.*;
import java.util.*;
public class hashing_search {
/* 哈希查找(数组) */
static int hashingSearch(Map<Integer, Integer> map, int target) {
// 哈希表的 key: 目标元素value: 索引
// 若哈希表中无此 key ,返回 -1
return map.getOrDefault(target, -1);
}
/* 哈希查找(链表) */
static ListNode hashingSearch1(Map<Integer, ListNode> map, int target) {
// 哈希表的 key: 目标结点值value: 结点对象
// 若哈希表中无此 key ,返回 -1
return map.getOrDefault(target, null);
}
public static void main(String[] args) {
int target = 3;
/* 哈希查找(数组) */
int[] nums = { 1, 5, 3, 2, 4, 7, 5, 9, 10, 8 };
// 初始化哈希表
Map<Integer, Integer> map = new HashMap<>();
for (int i = 0; i < nums.length; i++) {
map.put(nums[i], i); // key: 元素value: 索引
}
int index = hashingSearch(map, target);
System.out.println("目标元素 3 的索引 = " + index);
/* 哈希查找(链表) */
ListNode head = ListNode.arrToLinkedList(nums);
// 初始化哈希表
Map<Integer, ListNode> map1 = new HashMap<>();
while (head != null) {
map1.put(head.val, head); // key: 结点值value: 结点
head = head.next;
}
ListNode node = hashingSearch1(map1, target);
System.out.println("目标结点值 3 的对应结点对象为 " + node);
}
}