题目描述:

输入 𝑛n 个不超过 109109 的单调不减的（就是后面的数字不小于前面的数字）非负整数 𝑎1,𝑎2,…,𝑎𝑛a1​,a2​,…,an​，然后进行 𝑚m 次询问。对于每次询问，给出一个整数 𝑞q，要求输出这个数字在序列中第一次出现的编号，如果没有找到的话输出 −1−1 。

代码:

package lanqiao;import java.util.*;public class Main {public static void main(String[] args) {Scanner sc = new Scanner(System.in);int n = sc.nextInt();int m = sc.nextInt();int[] num = new int[n + 1];for(int i = 1;i <= n;i ++){num[i] = sc.nextInt();}while(m -- > 0){int target = sc.nextInt();int left = 1;int right = n;//二分模板while(left < right){int mid = (left + right)/2;if(num[mid] < target){left = mid + 1;}else{right = mid;}}if(num[left] == target){System.out.print(left + " ");}else{System.out.print(-1 + " ");}}}
}