CF1137B Camp Schedule

#include <iostream>
#include <cstring>
using namespace std;
const int N=500000+10;
int Next[N];
char s[N],t[N];

void GET_next(char* t, int Next[])
{
    int j = 0;
    int len=strlen(t+1);
    for(int i = 2; i <= len; i++){
        while(j && t[j+1] != t[i]){
            j = Next[j];
        }
        if(t[j+1] == t[i]) j++;
        Next[i] = j;
    }
}

int main()
{
    scanf("%s",s+1);
    scanf("%s",t+1);
    int l1=strlen(s+1);
    int l2=strlen(t+1);
    int s0=0,s1=0;
    
    for (int i=1;i<=l1;i++){
        if (s[i]==‘0‘) s0++;
        else s1++;
    }
    GET_next(t,Next);
    int j=1;
    for (int i=1;i<=l1;i++){
        if (t[j]==‘0‘){
            if (s0) {
                cout<<0;s0--;
            }
            else break;
        }
        else{
            if (s1) {
                cout<<1;s1--;
            }
            else break;
        }
        j++;
        if (j==l2+1) j=Next[l2]+1;
    }
    if (s0) for (int i=1;i<=s0;i++) cout<<0;
    if (s1) for (int i=1;i<=s1;i++) cout<<1;
    return 0;
}