Codeforces Round #350 (Div. 2) F. Restore a Number 模拟构造题

#include<bits/stdc++.h>
using namespace std;
const int N = 3e6+20, M = 1e6+10, mod = 1e9+7, inf = 1e9+1000;
typedef long long ll;

int H[N];
vector<string > ans;
char a[N],sub[N];
int b[N],Sub,y[1001];
int pushdown(int len) {
    for(int i=0;i<=9;i++) H[i]-=y[i];
    int tmp = len,can = 1;
        while(tmp) {
            if(H[tmp%10]) H[tmp%10] = H[tmp%10]- 1;
            else {can = 0;H[tmp%10] = H[tmp%10]- 1;}
            tmp/=10;
    }
    int sum = 0;for(int i=0;i<=9;i++) H[i]+=y[i];
    for(int i=0;i<=9;i++) sum+=H[i];

    if(sum!=len||!can) {
        tmp = len;
        while(tmp) {
            H[tmp%10] = H[tmp%10] + 1;
            tmp/=10;
        }
        return 0;
    }
    else return 1;
}

int main() {
    scanf("%s",a+1);
    int L = strlen(a+1);
    getchar();gets(sub+1);
    Sub = strlen(sub+1);
    for(int i=1;i<=L;i++) H[a[i]-‘0‘]++;
    if(L==2&&H[0]==1&&H[1]==1) {printf("0\n");return 0;}
    for(int i=1;i<=Sub;i++) y[sub[i]-‘0‘]++;
    for(int len = 1;;len++) {
        if(!pushdown(len))continue;

           for(int i=0;i<=9;i++) H[i]-=y[i];
        int fir ,cnt = 0;
        for(int i=0;i<=9;i++) {
            for(int j=1;j<=H[i];j++) {
                b[++cnt] = i;
            }
        }
        //如果全部为0的情况
        if(b[cnt]==0&&sub[1]!=‘0‘) {
            for(int i=1;i<=Sub;i++) printf("%c",sub[i]);
            for(int i=1;i<=cnt;i++) printf("%c",b[i]+‘0‘);
        }
        else {//找到Sub对应的位置就好了
           //     cout<<1<<endl;
            for(int i=1;i<=cnt;i++) {
                if(b[i]) {
                    swap(b[1],b[i]);
                    break;
                }
            }
            if(Sub==0) {
                for(int i=1;i<=cnt;i++) printf("%c",b[i]+‘0‘);
                return 0;
            }

             int f = -1;
                    for(int j=2;j<=Sub;j++) {
                        if(sub[j]>sub[j-1]) {
                            f=1;break;
                        }
                        else if(sub[j]<sub[j-1]) {f=0;break;}
                        else continue;
                    }
            int yes = 1;
            for(int i=1;i<=cnt;) {
                if(i==1&&sub[1]!=‘0‘) {
                    int l = 1,can = 1;
                    while(l<=Sub&&l<=cnt) {
                        if(b[l]+‘0‘<sub[l]) {can = 0;break;}
                        else if(b[l]+‘0‘>sub[l]) {can = 1;break;}
                        else {l++;}
                    }
                    if(can) {
                        cout<<sub+1;
                        sort(b+1,b+cnt+1);
                        yes = 0;
                    }
                     printf("%c",b[i++]+‘0‘);continue;
                }
                else if(i==1){
                    printf("%c",b[i++]+‘0‘);
                    continue;
                }
                if(!yes) printf("%c",b[i++]+‘0‘);
                else {
                    int l = i;
                    int tmp = 1;
                    while(l<=cnt&&b[l]+‘0‘<sub[tmp]) {
                        printf("%c",b[l++]+‘0‘);
                    }

                    if(f<=0) {
                        printf("%s",sub+1);
                    }
                    else {
                        while(l<=cnt&&b[l]+‘0‘==sub[tmp]) {
                         printf("%c",b[l++]+‘0‘);
                        }
                         printf("%s",sub+1);
                    }
                    yes = 0;
                    i = l;
                }
            }
            if(yes) cout<<sub+1;
        }

       // cout<<" "<<len<<endl;
        printf("\n");return 0;
    }
    return 0;
}