You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
64 lines
2.4 KiB
64 lines
2.4 KiB
/**
|
|
* File: binary_search_insertion.java
|
|
* Created Time: 2023-08-04
|
|
* Author: Krahets (krahets@163.com)
|
|
*/
|
|
|
|
package chapter_searching;
|
|
|
|
class binary_search_insertion {
|
|
/* 二分查找插入点（无重复元素） */
|
|
static int binarySearchInsertionSimple(int[] nums, int target) {
|
|
int i = 0, j = nums.length - 1; // 初始化双闭区间 [0, n-1]
|
|
while (i <= j) {
|
|
int m = i + (j - i) / 2; // 计算中点索引 m
|
|
if (nums[m] < target) {
|
|
i = m + 1; // target 在区间 [m+1, j] 中
|
|
} else if (nums[m] > target) {
|
|
j = m - 1; // target 在区间 [i, m-1] 中
|
|
} else {
|
|
return m; // 找到 target ，返回插入点 m
|
|
}
|
|
}
|
|
// 未找到 target ，返回插入点 i
|
|
return i;
|
|
}
|
|
|
|
/* 二分查找插入点（存在重复元素） */
|
|
static int binarySearchInsertion(int[] nums, int target) {
|
|
int i = 0, j = nums.length - 1; // 初始化双闭区间 [0, n-1]
|
|
while (i <= j) {
|
|
int m = i + (j - i) / 2; // 计算中点索引 m
|
|
if (nums[m] < target) {
|
|
i = m + 1; // target 在区间 [m+1, j] 中
|
|
} else if (nums[m] > target) {
|
|
j = m - 1; // target 在区间 [i, m-1] 中
|
|
} else {
|
|
j = m - 1; // 首个小于 target 的元素在区间 [i, m-1] 中
|
|
}
|
|
}
|
|
// 返回插入点 i
|
|
return i;
|
|
}
|
|
|
|
public static void main(String[] args) {
|
|
// 无重复元素的数组
|
|
int[] nums = { 1, 3, 6, 8, 12, 15, 23, 26, 31, 35 };
|
|
System.out.println("\n数组 nums = " + java.util.Arrays.toString(nums));
|
|
// 二分查找插入点
|
|
for (int target : new int[] { 6, 9 }) {
|
|
int index = binarySearchInsertionSimple(nums, target);
|
|
System.out.println("元素 " + target + " 的插入点的索引为 " + index);
|
|
}
|
|
|
|
// 包含重复元素的数组
|
|
nums = new int[] { 1, 3, 6, 6, 6, 6, 6, 10, 12, 15 };
|
|
System.out.println("\n数组 nums = " + java.util.Arrays.toString(nums));
|
|
// 二分查找插入点
|
|
for (int target : new int[] { 2, 6, 20 }) {
|
|
int index = binarySearchInsertion(nums, target);
|
|
System.out.println("元素 " + target + " 的插入点的索引为 " + index);
|
|
}
|
|
}
|
|
}
|