【CF1025A】Doggo Recoloring（签到）

题意：给定一个长度为 n 的小写字母串。可以将出现次数大于等于2的字母全部变成另一个小写字母，问最后能否将该小写字母串的所有字母变成同一个字母

n<=1e5

思路：

 #include<cstdio>
 #include<cstring>
 #include<string>
 #include<cmath>
 #include<iostream>
 #include<algorithm>
 #include<map>
 #include<set>
 #include<queue>
 #include<vector>
 using namespace std;
 typedef long long ll;
 typedef unsigned int uint;
 typedef unsigned long long ull;
 typedef pair<int,int> PII;
 typedef vector<int> VI;
 #define fi first
 #define se second
 #define MP make_pair
 #define N   1100000
 #define MOD 1000000007
 #define eps 1e-8
 #define pi acos(-1)
 #define oo 110000000000000

 char a[N];
 int b[N],c[N];

 int read()
 {
    int v=,f=;
    char c=getchar();
    while(c<||<c) {if(c=='-') f=-; c=getchar();}
    while(<=c&&c<=) v=(v<<)+v+v+c-,c=getchar();
    return v*f;
 }

 void swap(int &x,int &y)
 {
     int t=x;x=y;y=t;
 }

 int main()
 {
     //freopen("1.in","r",stdin);
     //freopen("1.out","w",stdout);
     int n;
     scanf("%d",&n);
     scanf("%s",a+);
     for(int i=;i<=n;i++) b[a[i]-'a'+]++;
     if(n==) printf("Yes\n");
      else
      {
          int flag=;
          for(int i=;i<=;i++)
           if(b[i]>=) flag=;
          if(flag) printf("Yes\n");
           else printf("No\n");
      }
     return ;
 }