Petya and Vasya decided to play a game. They have n cards (n is an even number). A single integer is written on each card.
Before the game Petya will choose an integer and after that Vasya will choose another integer (different from the number that Petya chose). During the game each player takes all the cards with number he chose. For example, if Petya chose number 5 before the game he will take all cards on which 5 is written and if Vasya chose number 10 before the game he will take all cards on which 10 is written.
The game is considered fair if Petya and Vasya can take all n cards, and the number of cards each player gets is the same.
Determine whether Petya and Vasya can choose integer numbers before the game so that the game is fair.
The first line contains a single integer n (2 ≤ n ≤ 100) — number of cards. It is guaranteed that n is an even number.
The following n lines contain a sequence of integers a1, a2, ..., an (one integer per line, 1 ≤ ai ≤ 100) — numbers written on the n cards.
If it is impossible for Petya and Vasya to choose numbers in such a way that the game will be fair, print "NO" (without quotes) in the first line. In this case you should not print anything more.
In the other case print "YES" (without quotes) in the first line. In the second line print two distinct integers — number that Petya should choose and the number that Vasya should choose to make the game fair. If there are several solutions, print any of them.
4
11
27
27
11
YES
11 27
2
6
6
NO
6
10
20
30
20
10
20
NO
6
1
1
2
2
3
3
NO
In the first example the game will be fair if, for example, Petya chooses number 11, and Vasya chooses number 27. Then the will take all cards — Petya will take cards 1 and 4, and Vasya will take cards 2 and 3. Thus, each of them will take exactly two cards.
In the second example fair game is impossible because the numbers written on the cards are equal, but the numbers that Petya and Vasya should choose should be distinct.
In the third example it is impossible to take all cards. Petya and Vasya can take at most five cards — for example, Petya can choose number 10 and Vasya can choose number 20. But for the game to be fair it is necessary to take 6 cards.
这个A很简单的,就是看下是不是两种牌,而且张数相等,因为他让你输出两张牌了
手残把O达成了0,真是石乐志,我这个字体看这个还是很明显的
#include<bits/stdc++.h> using namespace std; const int N=100005; int main() { int n; cin>>n; map<int,int>M; int x; for(int i=0;i<n;i++) { cin>>x; M[x]++; } if(M.size()==2&&M[x]==n/2) { printf("YES "); for(auto X:M) { printf("%d ",X.first); } } else printf("NO "); return 0; }
Polycarp loves lowercase letters and dislikes uppercase ones. Once he got a string s consisting only of lowercase and uppercase Latin letters.
Let A be a set of positions in the string. Let's call it pretty if following conditions are met:
- letters on positions from A in the string are all distinct and lowercase;
- there are no uppercase letters in the string which are situated between positions from A (i.e. there is no such j that s[j] is an uppercase letter, and a1 < j < a2 for some a1 and a2 from A).
Write a program that will determine the maximum number of elements in a pretty set of positions.
The first line contains a single integer n (1 ≤ n ≤ 200) — length of string s.
The second line contains a string s consisting of lowercase and uppercase Latin letters.
Print maximum number of elements in pretty set of positions for string s.
11
aaaaBaabAbA
2
12
zACaAbbaazzC
3
3
ABC
0
In the first example the desired positions might be 6 and 8 or 7 and 8. Positions 6 and 7 contain letters 'a', position 8 contains letter 'b'. The pair of positions 1 and 8 is not suitable because there is an uppercase letter 'B' between these position.
In the second example desired positions can be 7, 8 and 11. There are other ways to choose pretty set consisting of three elements.
In the third example the given string s does not contain any lowercase letters, so the answer is 0.
B实际是是求连续的小写字母中小写字母的种数
#include<bits/stdc++.h> using namespace std; const int N=100005; int main() { int n; cin>>n; string s; cin>>s; int c=0; set<char>S; for(int i=0; i<n; i++) { S.clear(); for(; i<n; i++) { if(s[i]>='a'&&s[i]<='z') S.insert(s[i]); else break; } c=max((int)S.size(),c); } c=max((int)S.size(),c); cout<<c; return 0; }