Secret Passwords CodeForces - 1263D（并查集）

One unknown hacker wants to get the admin’s password of AtForces testing system, to get problems from the next contest. To achieve that, he sneaked into the administrator’s office and stole a piece of paper with a list of n passwords — strings, consists of small Latin letters.

Hacker went home and started preparing to hack AtForces. He found that the system contains only passwords from the stolen list and that the system determines the equivalence of the passwords a and b as follows:

two passwords a and b are equivalent if there is a letter, that exists in both a and b;
two passwords a and b are equivalent if there is a password c from the list, which is equivalent to both a and b.
If a password is set in the system and an equivalent one is applied to access the system, then the user is accessed into the system.

For example, if the list contain passwords “a”, “b”, “ab”, “d”, then passwords “a”, “b”, “ab” are equivalent to each other, but the password “d” is not equivalent to any other password from list. In other words, if:

admin’s password is “b”, then you can access to system by using any of this passwords: “a”, “b”, “ab”;
admin’s password is “d”, then you can access to system by using only “d”.
Only one password from the list is the admin’s password from the testing system. Help hacker to calculate the minimal number of passwords, required to guaranteed access to the system. Keep in mind that the hacker does not know which password is set in the system.

Input
The first line contain integer n (1≤n≤2⋅105) — number of passwords in the list. Next n lines contains passwords from the list – non-empty strings si, with length at most 50 letters. Some of the passwords may be equal.

It is guaranteed that the total length of all passwords does not exceed 106 letters. All of them consist only of lowercase Latin letters.

Output
In a single line print the minimal number of passwords, the use of which will allow guaranteed to access the system.

Examples
Input
4
a
b
ab
d
Output
2
Input
3
ab
bc
abc
Output
1
Input
1
codeforces
Output
1
Note
In the second example hacker need to use any of the passwords to access the system.
思路：密码相同有两种规则，如果含有相同的字母或者同时和另一个密码相同。那么我们就把这n个字符串中的字母，出现在同一字母中的利用并查集更新为一个集合。最后查找出现的这几个字母中，有几个祖先就可以了。
代码如下：

#include<bits/stdc++.h>
#define ll long long
using namespace std;const int maxx=30;
int f[maxx];
string s;
int n,len;inline void init()
{for(int i=0;i<=26;i++) f[i]=i;
}
inline int getf(int u)
{return u==f[u]?u:f[u]=getf(f[u]);
}
inline void merge(int u,int v)
{int t1=getf(u);int t2=getf(v);if(t1!=t2) f[t1]=t2;
}
int main()
{scanf("%d",&n);init();set<int> se;for(int i=1;i<=n;i++){cin>>s;len=s.length();for(int j=1;j<len;j++) merge(s[j]-'a',s[j-1]-'a');for(int j=0;j<len;j++) se.insert(s[j]-'a');}map<int,bool> mp;int ans=0;for(set<int> ::iterator it=se.begin();it!=se.end();it++){int zz=getf(*it);if(!mp[zz]) mp[zz]=1,ans++;}cout<<ans<<endl;return 0;
}

努力加油a啊，(^o)/~

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