CodeForces-701C They Are Everywhere

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/Mr_Qin_AC/article/details/82863212

# include<stdio.h>
# include<string.h>
# include<algorithm>
# include<math.h>
using namespace std;
char s[100005];
int c[60];
int vis[60];
int id(char ch){
	if(ch>='a'&&ch<='z'){
		return ch-'a';
	}
	else{
		return ch-'A'+26;
	}
}
int main(){
	int n,num=0;
	scanf("%d",&n);
	scanf("%s",s+1);
	memset(vis,0,sizeof(vis));
	for(int i=1;i<=n;i++){
		if(!vis[id(s[i])]){
			num++;
			vis[id(s[i])]=1;
		}
	}
	memset(vis,0,sizeof(vis));
	int cnt=0,l=1,r,ans=0;
	for(int i=1;i<=n;i++){
		if(cnt==num){
			break;
		}
		if(!vis[id(s[i])]){
			cnt++;
		}
		vis[id(s[i])]++;
		r=i;
		ans++;
	}
	while(r<=n){
      while(vis[id(s[l])]>1){
      	vis[id(s[l])]--;
      	l++;
	  }		
	  ans=min(ans,r-l+1);
	  r++;
	  if(r>n){
	  	break;
	  }
	  vis[id(s[r])]++;
	}
	printf("%d\n",ans);
	return 0;
}