cf1104 codeforces round 534(div2) B. Game with string(STL)

第一次发现string 的erase函数是o(1)的复杂度，直接模拟

#include<bits/stdc++.h>
using namespace std;
int book[100010];
int main()
{
    string s;
    cin>>s;
    int len=s.size()-1;
    int cnt=0;
    for(int i=0;s[i];i++)
    {
        //printf("**%d
",i);
        if(s[i]==s[i+1])
        {
            //printf("%d ",i);
            cnt++;
            s.erase(s.begin()+i);
            //cout<<s<<endl;
            s.erase(s.begin()+i);
            if(i==0)
              i--;
            else
              i-=2;
            //cout<<s<<endl;
            //printf("%d
",cnt);
        }
    }
    if(cnt%2==1)
      printf("Yes
");
    else
      printf("No
");
}

还可以用栈，如果发现入栈的字符和栈顶相同,cnt++,并弹出栈顶

#include<bits/stdc++.h>
#define int long long
#define MAX(a,b,c) max(a,max(b,c))
#define MIN(a,b,c) min(a,min(b,c))
#define pb push_back
#define fi first
#define se second
typedef long long ll;
typedef long long LL;
typedef unsigned long long ull;
typedef unsigned long long uLL;
using namespace std;
const int maxn=1e6+10;
const int mod=1e9+10;
int32_t main()
{
     string ss; cin>>ss;
     int ans=0;
     stack<char> st;
     for(int i=0;i<ss.size();i++)
     {
         if(st.size()==0) st.push(ss[i]);
         else
         {
             if(ss[i]==st.top())
             {
                 ans++; st.pop();
             }
             else
             {
                 st.push(ss[i]);
             }
         }
     }
     if(ans%2==0) cout<<"No"<<endl;
     else       cout<<"Yes"<<endl;
}