必须是有序的数组才能进行二分查找
- package cn.sunzn.dichotomy;
- public class DichotomySearch {
- public static void main(String[] args) {
- int[] arr = new int[] { 12, 23, 34, 45, 56, 67, 77, 89, 90 };
- System.out.println(search(arr, 12));
- System.out.println(search(arr, 45));
- System.out.println(search(arr, 67));
- System.out.println(search(arr, 89));
- System.out.println(search(arr, 99));
- }
- public static int search(int[] arr, int key) {
- int start = 0;
- int end = arr.length - 1;
- while (start <= end) {
- int middle = (start + end) / 2;
- if (key < arr[middle]) {
- end = middle - 1;
- } else if (key > arr[middle]) {
- start = middle + 1;
- } else {
- return middle;
- }
- }
- return -1;
- }
- }[b][/b]
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