B. Game with string（cf）STL：stack
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output
Two people are playing a game with a string ss, consisting of lowercase latin letters.
On a player's turn, he should choose two consecutive equal letters in the string and delete them.
For example, if the string is equal to "xaax" than there is only one possible turn: delete "aa", so the string will become "xx". A player not able to make a turn loses.
Your task is to determine which player will win if both play optimally.
Input
The only line contains the string ss, consisting of lowercase latin letters (1≤|s|≤1000001≤|s|≤100000), where |s||s| means the length of a string ss.
Output
If the first player wins, print "Yes". If the second player wins, print "No".
Examples
input
abacaba
output
No
input
iiq
output
Copy
Yes
input
abba
output
No
Note
In the first example the first player is unable to make a turn, so he loses.
In the second example first player turns the string into "q", then second player is unable to move, so he loses.
#include <bits/stdc++.h>
using namespace std;
#define ll long long int
int main()
{
string str;
stack<char>s;
cin>>str;
int num=0;
for(int i=0;i<str.length();i++)
{
if(!s.empty()&&str[i]==s.top())//一定要先判空
{
num++;
s.pop();
}
else
s.push(str[i]);
}
if(num&1)
cout<<"Yes"<<endl;
else
cout<<"No"<<endl;
return 0;
}
