Codeforces Round #445 B. Vlad and Cafes【时间轴】
Vlad likes to eat in cafes very much. During his life, he has visited cafes n times. Unfortunately, Vlad started to feel that his last visits are not any different from each other. To fix that Vlad had a small research.
First of all, Vlad assigned individual indices to all cafes. Then, he wrote down indices of cafes he visited in a row, in order of visiting them. Now, Vlad wants to find such a cafe that his last visit to that cafe was before his last visits to every other cafe. In other words, he wants to find such a cafe that he hasn't been there for as long as possible. Help Vlad to find that cafe.
In first line there is one integer n (1 ≤ n ≤ 2·105) — number of cafes indices written by Vlad.
In second line, n numbers a1, a2, ..., an (0 ≤ ai ≤ 2·105) are written — indices of cafes in order of being visited by Vlad. Vlad could visit some cafes more than once. Note that in numeration, some indices could be omitted.
Print one integer — index of the cafe that Vlad hasn't visited for as long as possible.
5
1 3 2 1 2
3
6
2 1 2 2 4 1
2
In first test, there are three cafes, and the last visits to cafes with indices 1 and 2 were after the last visit to cafe with index 3; so this cafe is the answer.
In second test case, there are also three cafes, but with indices 1, 2 and 4. Cafes with indices 1 and 4 were visited after the last visit of cafe with index 2, so the answer is 2. Note that Vlad could omit some numbers while numerating the cafes.
【题意】: 找到一个数满足,它最后一次出现的位置是i,位置i+1到n所有其他数字都出现过至少一次 。
【分析】: 1.上一次当彼佳参观每一家咖啡馆时,将其放在数组中。 2.现在你需要找到这个数组中最小的位置并打印它。
【代码】:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
#include <bits/stdc++.h> using namespace std; const int maxn = 1e5+1e5+10; const int inf = 9999999; int vis[maxn]; int main() { int n,a; int min; int m; while(cin>>n) { min=1000000,m=-1; for(int i=1;i<=n;i++) { cin>>a; vis[a]=i; } for(int i=0;i<=200000;i++) { if(vis[i]&&vis[i]<min) { min=vis[i]; m=i; } } cout<<m<<endl; } }