（AC）Playlist

题目描述

You are given a playlist of a radio station since its establishment. The playlist has a total of n songs.

What is the longest sequence of successive songs where each song is unique?

输入

The first input line contains an integer n(1 ≤ n ≤ 2*105): the number of songs.

The next line has n integers k1,k2,...,kn(1 ≤ ki ≤ 109): the id number of each song.

输出

Print the length of the longest sequence of unique songs.

样例输入 Copy

8
1 2 1 3 2 7 4 2

样例输出 Copy

5

代码

#include<bits/stdc++.h>
using namespace std;
int n,k[200009];
int main(){
	cin>>n;
	for(int i=0;i<n;++i)cin>>k[i];
	map<int,int>book;
	int ans=0,l=0,r=-1;
	for(int i=0;i<n;++i){
		if(book[k[i]]){
			ans=ans>(r-l+1)?ans:r-l+1;
			while(book[k[i]]&&l<=r){
				book[k[l]]--;
				l++;
			}
		}
		r++;
		book[k[i]]++;
	}
	ans=ans>(r-l+1)?ans:r-l+1;
	cout<<ans;
	return 0;
}