https://poki.com/zh/g/puppet-master

#include<bits/stdc++.h>
using namespace std;
int main(){
string s;
cin>>s;
int a=-1,b=-1;
for(int i=0;i<s.size();i++){
if(s[i]=='1'){
a=i;
break;
}
}
for(int i=s.size()-1;i>=0;i--){
if(s[i]=='0'&&i>a){
b=i;
break;
}
}

if(a==-1||b==-1){
cout<<s;
}else{
reverse(s.begin()+a,s.begin()+b+1);
cout<<s;
}

return 0;
}

#include <bits/stdc++.h>
using namespace std;
int main() {
long long n;
cin>>n;
long long a;
long long s=0;
for(int i=1;i<=n;i++){
cin>>a;
long long z=a/1000;
long long b=a/100%10;
long long v=a/10%10;
long long o=a%10;
if(o-v-b-z>0){
s++;
}
}
cout<<s;

return 0;
}

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#include<bits/stdc++.h>
using namespace std;
int n;
int a[10005];
int dp[10005];
long long s[10005];
int main(){
cin>>n;
for(int i=1;i<=n;i++){
cin>>a[i];
s[i]=s[i-1]+a[i];
}
if(s[n]<0){
cout<<"Impossible";
return 0;
}
for(int i=1;i<=n;i++){
int mx=0;
for(int k=1;k<=i-1;k++){
if(a[k]<a[i]){
mx=max(dp[k],mx);
}
}
dp[i]=mx+1;
}

for(int i=1;i<=n;i++){
if(s[i]>=0){
int mx=INT_MIN;
for(int j=1;j<i;j++){
if(s[i]){
mx=max(mx)
}
}
}
dp[i]=mx;
}
cout<<dp[n];


return 0;
}