Codeforces828 C. String Reconstruction

字符串重构算法

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本文介绍了一个字符串重构问题，目标是根据给定的子串出现次数及其位置信息，构造出一个字典序最小的字符串。通过逐个处理每个字符信息并利用位置递增特性，避免重复覆盖，最终生成符合条件的字符串。

Ivan had string s consisting of small English letters. However, his friend Julia decided to make fun of him and hid the string s. Ivan preferred making a new string to finding the old one.

Ivan knows some information about the string s. Namely, he remembers, that string ti occurs in string s at least ki times or more, he also remembers exactly ki positions where the string ti occurs in string s: these positions are xi, 1, xi, 2, ..., xi, ki. He remembers n such strings ti.

You are to reconstruct lexicographically minimal string s such that it fits all the information Ivan remembers. Strings ti and string s consist of small English letters only.

Input

The first line contains single integer n (1 ≤ n ≤ 105) — the number of strings Ivan remembers.

The next n lines contain information about the strings. The i-th of these lines contains non-empty string ti, then positive integer ki, which equal to the number of times the string ti occurs in string s, and then ki distinct positive integers xi, 1, xi, 2, ..., xi, ki in increasing order — positions, in which occurrences of the string ti in the string s start. It is guaranteed that the sum of lengths of strings ti doesn't exceed 106, 1 ≤ xi, j ≤ 106, 1 ≤ ki ≤ 106, and the sum of all ki doesn't exceed 106. The strings ti can coincide.

It is guaranteed that the input data is not self-contradictory, and thus at least one answer always exists.

Output

Print lexicographically minimal string that fits all the information Ivan remembers.

        Examples
      

          input
        
3
a 4 1 3 5 7
ab 2 1 5
ca 1 4

          output
        
abacaba

          input
        
1
a 1 3

          output
        
aaa

          input
        
3
ab 1 1
aba 1 3
ab 2 3 5

          output
        
ababab

#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <algorithm>
#include <cmath>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <vector>
#include <bitset>

using namespace std;

#define LL long long
const int INF = 0x3f3f3f3f;
#define MAXN 500

char s[2000006];
char ch[2000005];
int main()
{
    int n,m,x;

    int tot=0;
    scanf("%d",&n);
    for(int i=0; i<n; i++)
    {
        scanf("%s%d",&ch,&m);
        int k=strlen(ch);
        int t=-INF;
        for(int j=0; j<m; j++)
        {
            scanf("%d",&x);
            x--;
            tot=max(x+k,tot);
            for(int l=max(x,t); l<x+k; l++)
                s[l]=ch[l-x];
            t=x+k;
        }
    }
    for(int i=0; i<tot; i++)
        if(s[i]=='\0')
            printf("a");
        else
            printf("%c",s[i]);
    printf("\n");

    return 0;
}