Java uses binary search method to implement sorting number index function example explanation-javaTutorial-php.cn

This article mainly introduces Java's use of the divide-and-conquer algorithm to implement the sorting index function, and analyzes the related operating techniques of the java divide-and-conquer algorithm for sorting indexing based on specific examples. Friends in need can refer to the following

The example in this article describes Java's use of the divide-and-conquer algorithm to implement the sorting index function. Share it with everyone for your reference, the details are as follows:

/** * Find the first q and return the index * First method is brutal force * Second may * be pid and Conquer * * @author open201 * */ public class Ono { /** * f(n) = s.length = n; * * @param s * @param q * @return */ public static int BrutalForceSearch(int[] s, int q) { for (int i = 0; i < s.length; i++) { if (q == s[i]) return i; } return -1; } /** * f(n) = log(n) * * @param s * @param q * @return */ public static int DCSearch(int[] s, int q, int startIndex, int endIndex) { if (startIndex > endIndex) return -1; else { int mid = (startIndex + endIndex) / 2; if (s[mid] == q) return mid; else { if (s[mid] > q) return DCSearch(s, q, startIndex,mid-1); else return DCSearch(s, q, mid+ 1,endIndex); } } } public static void main(String[] args) { int [] s = new int[10000000]; for(int i = 0;i<10000000;i++){ s[i] = i; } int q = 10000000-1; long startTime = System.currentTimeMillis(); System.out.println(BrutalForceSearch(s, q)); long endTime = System.currentTimeMillis(); System.out.println(endTime-startTime); startTime = System.currentTimeMillis(); System.out.println(DCSearch(s, q, 0, s.length - 1)); endTime = System.currentTimeMillis(); System.out.println(endTime-startTime); } }

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