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题解：AtCoder AT_awc0002_a Organizing the Bookshelf

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本文分享的必刷题目是从蓝桥云课、洛谷、AcWing等知名刷题平台精心挑选而来，并结合各平台提供的算法标签和难度等级进行了系统分类。题目涵盖了从基础到进阶的多种算法和数据结构，旨在为不同阶段的编程学习者提供一条清晰、平稳的学习提升路径。

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【题目来源】

AtCoder：A - Organizing the Bookshelf (atcoder.jp)

【题目描述】

Takahashi works at a library. On a bookshelf in the library,N NNbooks are lined up in a row, and each book has a catalog number assigned to it. The catalog number of thei ii-th book from the left (1 ≤ i ≤ N 1≤i≤N1≤i≤N) isA i A_iAi. Note that different books may have the same catalog number.
高桥在图书馆工作。图书馆的书架上有一排N NN本书，每本书都分配有一个书目编号。从左数第i ii本书（1 ≤ i ≤ N 1 ≤ i ≤ N1≤i≤N）的书目编号为A i A_iAi。注意，不同的书可能具有相同的书目编号。

Aoki asks, “I’m looking for the book with catalog numberK KK. Where is it?”
青木问道：“我正在寻找书目编号为K KK的书。它在哪里？”

Among theN NNbooks on the bookshelf, find the book whose catalog number is exactlyK KK. If a book with catalog numberK KKexists, output the smallest position of such a book (counted from the left, 1-indexed). If no such book exists, output−1.
在书架上的N NN本书中，找到书目编号恰好为K KK的书。如果存在书目编号为K KK的书，输出这类书中位置最靠左的书的位置（从左计数，从1 11开始编号）。如果不存在这样的书，输出-1。

【输入】

N NNK KK
A 1 A 2 … A N A_1\ A_2\dots A_NA1A2…AN

The first line contains an integerN NNrepresenting the number of books and an integerK KKrepresenting the catalog number being searched for, separated by a space.
The second line contains integersA 1 , A 2 , … , A N A_1,A_2,…,A_NA1,A2,…,ANrepresenting the catalog numbers of the books, separated by spaces.

【输出】

If a book with catalog number exactlyK KKexists, output on a single line the smallest position of such a book (counted from the left, 1-indexed). If no such book exists, output−1.

【输入样例】

5 3 1 4 3 2 3

【输出样例】

【算法标签】

#模拟#

【解题思路】

【代码详解】

#include<bits/stdc++.h>usingnamespacestd;intn,k;// n: 序列长度，k: 要查找的数intmain(){cin>>n>>k;// 读入序列长度和要查找的数intpos=1;// 当前位置，从1开始计数for(inti=1;i<=n;i++){intx;cin>>x;// 读入当前数if(x==k)// 如果找到目标数{cout<<pos<<endl;// 输出当前位置return0;// 结束程序}pos++;// 当前位置加1}// 如果循环结束后仍然没有找到if(pos==n+1)// 等价于 i==n+1{cout<<-1<<endl;// 输出-1表示未找到}return0;}