POJ Find them, Catch them
Find them, Catch them
Time Limit: 1000MS | Memory Limit: 10000K | |
Total Submissions: 21858 | Accepted: 6513 |
Description
The police office in Tadu City decides to say ends to the chaos, as launch actions to root up the TWO gangs in the city, Gang Dragon and Gang Snake. However, the police first needs to identify which gang a criminal belongs to. The present question is, given two criminals; do they belong to a same clan? You must give your judgment based on incomplete information. (Since the gangsters are always acting secretly.)
Assume N (N <= 10^5) criminals are currently in Tadu City, numbered from 1 to N. And of course, at least one of them belongs to Gang Dragon, and the same for Gang Snake. You will be given M (M <= 10^5) messages in sequence, which are in the following two kinds:
1. D [a] [b]
where [a] and [b] are the numbers of two criminals, and they belong to different gangs.
2. A [a] [b]
where [a] and [b] are the numbers of two criminals. This requires you to decide whether a and b belong to a same gang.
Assume N (N <= 10^5) criminals are currently in Tadu City, numbered from 1 to N. And of course, at least one of them belongs to Gang Dragon, and the same for Gang Snake. You will be given M (M <= 10^5) messages in sequence, which are in the following two kinds:
1. D [a] [b]
where [a] and [b] are the numbers of two criminals, and they belong to different gangs.
2. A [a] [b]
where [a] and [b] are the numbers of two criminals. This requires you to decide whether a and b belong to a same gang.
Input
The
first line of the input contains a single integer T (1 <= T <=
20), the number of test cases. Then T cases follow. Each test case
begins with a line with two integers N and M, followed by M lines each
containing one message as described above.
Output
For
each message "A [a] [b]" in each case, your program should give the
judgment based on the information got before. The answers might be one
of "In the same gang.", "In different gangs." and "Not sure yet."
Sample Input
1 5 5 A 1 2 D 1 2 A 1 2 D 2 4 A 1 4
Sample Output
Not sure yet. In different gangs. In the same gang.
Source
并查集,relation[x] = 0 表示同一个帮派的 , 本题关键是如何压缩路径;
View Code
1 #include<stdio.h> 2 int father[101000],relation[101000] ; 3 void Init(int n){ 4 for(int i=1;i<=n;i++) 5 father[i] = i , relation[i] = 0; 6 } 7 int find(int x){ 8 if(x != father[x] ){ 9 int temp = father[x] ; 10 father[x] = find(father[x]) ; 11 relation[x] = (relation[temp] + relation[x] ) % 2; 12 } 13 return father[x] ; 14 } 15 void Union(int x,int y){ 16 int fx = find(x); 17 int fy = find(y); 18 if(fx != fy){ 19 father[fx] = fy ; 20 relation[fx] = (relation[x] + relation[y] + 1) % 2 ; 21 } 22 } 23 int main(){ 24 int T; 25 scanf("%d",&T); 26 while(T--){ 27 int n,m; 28 scanf("%d%d",&n,&m); 29 Init(n); 30 while(m--){ 31 char s[2] ; 32 int x , y; 33 scanf("%s%d%d",s,&x,&y); 34 if(s[0] == 'D'){ 35 Union(x,y); 36 } else{ 37 int fx = find(x) ; 38 int fy = find(y) ; 39 if(fx == fy){ 40 if(relation[x] == relation[y]) 41 printf("In the same gang.\n"); 42 else 43 printf("In different gangs.\n"); 44 } else 45 printf("Not sure yet.\n") ; 46 } 47 } 48 } 49 return 0; 50 }