CodeForces - 827A:String Reconstruction (基础并查集)
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 tioccurs 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
3
a 4 1 3 5 7
ab 2 1 5
ca 1 4
abacaba
1
a 1 3
aaa
3
ab 1 1
aba 1 3
ab 2 3 5
ababab
题意:给定一个字符串的部分消息,让你将其补齐,并且字典序最小。
思路:给出的消息可以得到字符串长度。现在就说需要把给出的消息都填进去,没有填到的部分用‘a’补齐,给出的消息很多重复的,直接for是不想的,我们用并查集快速的得到后面的第一个空着的位置。
(常规操作,居然想不到。。。
#include<bits/stdc++.h> #define rep(i,a,b) for(int i=a;i<=b;i++) using namespace std; const int maxn=2000010; char c[maxn]; int ans[maxn],fa[maxn]; int find(int x){ if(x!=fa[x]) fa[x]=find(fa[x]); return fa[x]; } int main() { int N,L=0; scanf("%d",&N); rep(i,1,2e6) fa[i]=i; rep(i,1,N){ scanf("%s",c+1); int Len=strlen(c+1),num; scanf("%d",&num); rep(j,1,num){ int x,pos; scanf("%d",&x); L=max(L,x+Len-1); pos=x; while(true){ pos=find(pos); if(pos>x+Len-1||!pos) break; ans[pos]=c[pos-x+1]; fa[pos]=fa[find(pos+1)]; pos=fa[pos]; } } } rep(i,1,L){ if(ans[i]=='\0') ans[i]='a'; putchar(ans[i]); } return 0; }