Java-二分查找算法

package XiaoMi;

import java.util.Scanner;

public class test9 {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner scan = new Scanner(System.in);
String str = scan.nextLine();
// System.out.println(str);

// 用子串实现-转换为数组
int[] n = new int[str.length()];
for (int i = 0; i < str.length(); i++) {
n[i] = Integer.parseInt(str.substring(i, i + 1)); // 很有用
}

/*
* // 暴力遍历，时间复杂度o(n) for(int i=0; i<n.length; i++){ if(n[i]>n[i+1]) {
* System.out.println("最小值为:" + n[i+1]); break; } }
*/

/*
* int temp =0; for(int i=0,m=(n.length+1)/2; i<m; i++ ){ int b =
* n.length-i-1; int a = 0;
*
* if(n[i]>n[b]){ //非顺序 temp = (n.length+1)/2; if(n[temp]>n[b]) { temp =
* ()/2; }else{
*
* } } }
*/
int num = 1;  //要查找的元素

int left = 0;
int right = n.length - 1;

for (int i = 0, m = (n.length + 1) / 2; i < m; i++) {
if (n[(left + right) / 2] == num) {
System.out.println("位置索引：" + (left + right) / 2);
break;
}
if (n[(left + right) / 2] > num) // 在左边
{
right = (left + right) / 2;
} else {
left = (left + right) / 2;
}
}

}

public static void search(int m, int n) {

}

}

123456
位置索引：0