-
[1218] You are my brother
- 时间限制: 1000 ms 内存限制: 131072 K
- 问题描述
-
Little A gets to know a new friend, Little B, recently. One day, they realize that they are family 500 years ago. Now, Little A wants to know whether Little B is his elder, younger or brother.
- 输入
-
There are multiple test cases.
For each test case, the first line has a single integer, n (n<=1000). The next n lines have two integers a and b (1<=a,b<=2000) each, indicating b is the father of a. One person has exactly one father, of course. Little A is numbered 1 and Little B is numbered 2.
Proceed to the end of file. - 输出
-
For each test case, if Little B is Little A’s younger, print “You are my younger”. Otherwise, if Little B is Little A’s elder, print “You are my elder”. Otherwise, print “You are my brother”. The output for each test case occupied exactly one line.
- 样例输入
-
5 1 3 2 4 3 5 4 6 5 6 6 1 3 2 4 3 5 4 6 5 7 6 7
- 样例输出
-
You are my elder You are my brother
- 提示
-
无
- 来源
-
辽宁省赛2010
题目意思很简单,输入N对数a,b,表示b是a的父亲,最后求的是1和2的关系,也就是树的深度。(注意,若a和b不在同一棵树上,则他们的关系为brother)
代码一:#include <cstring> #include <cstdio> int main() { int n,x,y; int ans[2005]; while(~scanf("%d",&n)) { memset(ans,0,sizeof(ans)); for(int i=0; i<n; i++) { scanf("%d%d",&x,&y); ans[x]=y; } int temp=1,a=0,b=0; while(ans[temp]){ a++; temp=ans[temp]; } temp=2; while(ans[temp]!=0) { b++; temp=ans[temp]; } if(a>b) printf("You are my elder\n"); else if(a<b) printf("You are my younger\n"); else printf("You are my brother\n"); } return 0; }
代码二:#include <cstdio> using namespace std; int main() { int n,x,y; int la,lb,a,b; while(~scanf("%d",&n)) { la=1; lb=2; a=0; b=0; while(n--){ scanf("%d%d",&x,&y); if(la!=lb) { if(x==la) { la=y; a++; } if(x==lb) { lb=y; b++; } } } if(a>b) printf("You are my elder\n"); else if(a<b) printf("You are my younger\n"); else printf("You are my brother\n"); } return 0; }
代码三:
#include <cstdio> int fa[2010]; int n,x,y; int Find(int x,int &H) { while(x != fa[x]) { x = fa[x]; H++; } return x; } int main() { while(~scanf("%d",&n)) { for(int i = 1; i <= 2000; i++) //用并查集时,初始化要注意上限,如果用n会TLE fa[i] = i; while(n--) { scanf("%d %d",&x,&y); fa[x] = y; } int a = 0 , b = 0 ; int f1 = Find( 1 , a ); int f2 = Find( 2 , b ); if(f1 != f2) //此时 1 和 2 并不在同一棵树上 printf("You are my brother\n"); else { if(a > b) printf("You are my elder\n"); else if(a < b) printf("You are my younger\n"); else printf("You are my brother\n"); } } return 0; }
以上代码 有一部分是根据网上题解思路所写的,据说这题还可以用 DFS+线段树来做,只是目前还没搞懂,等待更新……