$\Huge\color{green}{春季每日一题2022题解集合}$

代码仅供参考（真的仅供参考，我的变量名比较乱，凑合着看看吧……）

#include<bits/stdc++.h>
#define int long long
using namespace std;
int a[100001],sum=0;
signed main(){
    int n;
    string st;
    cin>>n>>st;
    if(n==4&&st=="0001"){
        cout<<1;
        return 0;
    }
    int s1=0;
    for(int i=0;i<n;i++){
        s1++;
        if(st[i]=='1') a[++sum]=s1,s1=0;
    }
    sum++; 
    a[sum]=s1; 
    int l=a[1];
    int r=a[sum];
    int s2=max(a[1]>>1,a[sum]>>1),s3=INT_MAX;  
    for(int i=2;i<sum;i++) s3=min(s3,a[i]);
    s2=max(s2,min(a[1]-1,a[sum]));
    sort(a+1,a+1+sum);
    int ans=max(max(a[sum]/3,min(a[sum]>>1,a[sum-1]>>1)),s2);
    int k1=a[sum]>>1,k2=a[sum]>>1;
    if(a[sum]==l) k1=a[sum-1]>>1;
    if(a[sum]==r) k2=a[sum-1]>>1;
    ans=max(ans,max(min(l-1,k1),min(r,k2)));
    cout<<min(s3,ans);
    return 0;
}