洛谷 2187 小Z的笔记

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<algorithm>
 4 #define LL long long
 5 #define rg register
 6 #define N 200010
 7 using namespace std;
 8 int n,m,ans,f[N],g[26];
 9 char s[N],c;
10 bool v[26][26];
11 inline int read(){
12     int k=0,f=1; char c=getchar();
13     while(c<‘0‘||c>‘9‘)c==‘-‘&&(f=-1),c=getchar();
14     while(‘0‘<=c&&c<=‘9‘)k=k*10+c-‘0‘,c=getchar();
15     return k*f;
16 }
17 int main(){
18     n=read();
19     scanf("%s",s+1);
20     m=read();
21     while(m--){
22         c=getchar(); while(c<‘a‘||c>‘z‘) c=getchar(); int x=c-‘a‘;
23         c=getchar(); while(c<‘a‘||c>‘z‘) c=getchar(); int y=c-‘a‘;
24         v[x][y]=v[y][x]=1;
25     }
26     for(rg int i=1;i<=n;i++){
27         for(rg int j=0;j<26;j++)if(!v[s[i]-‘a‘][j]){
28             f[i]=max(f[i],g[j]+1);
29         }
30         g[s[i]-‘a‘]=max(g[s[i]-‘a‘],f[i]);
31         ans=max(ans,f[i]);
32     }
33     printf("%d\n",n-ans);
34     return 0;
35 }