- 基本思想
首先将给定的值K与表中中间位置元素比较,若相等,则查找成功;若不等,则所需查找的元素只能在中间数据以外的前半部分或者后半部分,缩小范围后继续进行同样的查找,如此反复,直到找到为止。
- 代码实现
/** * 源码名称:BinarySearch.java * 日期:2014-08-14 * 程序功能:二分查找 * 版权:[email protected] * 作者:A2BGeek */ public class BinarySearch { public static int binarySearch(int[] in, int key) { int start = 0; int end = in.length - 1; int index = -1; while (start <= end) { // int mid = (start + end) / 2;会溢出 // int mid = start + (end - start) / 2; int mid = start + ((end - start) >> 2); // int mid = (start + end) >>> 1; if (key < in[mid]) { end = mid - 1; } else if (key > in[mid]) { start = mid + 1; } else { index = mid; break; } } return index; } public static int binarySearchRecursive(int[] in, int key, int start, int end) { if (start <= end) { int mid = start + ((end - start) >> 2); if (key < in[mid]) { end = mid - 1; return binarySearchRecursive(in, key, start, end); } else if (key > in[mid]) { start = mid + 1; return binarySearchRecursive(in, key, start, end); } else { return mid; } } else { return -1; } } public static void main(String[] args) { int[] testCase = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 20, 36 }; System.out.println(binarySearch(testCase, 12)); System.out.println(binarySearchRecursive(testCase, 12, 0, testCase.length - 1)); } }
【数据结构与算法】二分查找
时间: 2024-10-18 12:50:16