解题思路:模拟,遍历每个位置如果他的下一个位置是数字就输出几个字符,如果不是字符就只输出一个
#include<bits/stdc++.h>
#define x first
#define y second
#define mem(h) memset(h,-1,sizeof h)
#define mcp(a,b) memcpy(a,b,sizeof b)
using namespace std;
typedef long long LL;
typedef unsigned long long ull;
typedef pair<int,int>PII;
typedef pair<double,double>PDD;
namespace IO{
inline LL read(){
LL o=0,f=1;char c=getchar();
while(c<'0'||c>'9'){
if(c=='-')f=-1;c=getchar();}
while(c>='0'&&c<='9'){
o=o*10+c-'0';c=getchar();}
return o*f;
}
}using namespace IO;
const int N=1e4+7,M=2e5+7,INF=0x3f3f3f3f,mod=1e8+7,P=131;
string s,ans;
int main(){
cin>>s;
for(int i=0;i<s.size();){
int cnt=0;
if(s[i+1]>='0'&&s[i+1]<='9'){
cnt=s[i+1]-'0';
for(int j=0;j<cnt;j++){
ans+=s[i];
}
i+=2;
}else{
ans+=s[i];
i+=1;
}
}
cout<<ans<<endl;
return 0;
}