codeforces 827A 并查集

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

构造出来一个最小字典序的字符串，使得其满足n个条件。这n个条件中每个条件有一个连续的子字符串。然后有Ki个位子，表示这些字符串出现的位子。保证有解，n个条件互相没有矛盾。

暴力赋值的话肯定会超时，所以用并查集维护每个位置的右边第一个空位置在哪。

#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>

using namespace std;

const int maxn = 2e6 + 10;
char s[maxn], t[maxn];
int fa[maxn];
int n;

int getfa(int u)
{
    if (fa[u] == u) return u;
    else return fa[u] = getfa(fa[u]);
}

void merge(int u, int v)
{
    int fu = getfa(u);
    int fv = getfa(v);
    fa[fu] = fv;
}
int main()
{
    scanf("%d", &n);
    for (int i = 0; i < maxn; i++)
    {
        fa[i] = i;
    }
    memset(s, 'a', sizeof(s));
    int k, l;
    int end = 0;
    for (int i = 0; i < n; i++)
    {
        scanf("%s %d", t, &k);
        int len = strlen(t);
        for (int j = 0; j < k; j++)
        {
            scanf("%d", &l);
            end = max(end, l + len - 1);
            int x = getfa(l);
            while (x <= l + len -1)
            {
                s[x] = t[x - l];
                merge(x, x + 1);
                x = getfa(x + 1);
            }
        }
    }
    for (int i = 1; i <= end; i++)
    {
        printf("%c", s[i]);
    }
    printf("\n");
    
    return 0;
}

codeforces 827A 并查集

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