标签：tps ever scan sample 自身 dice c11 not tabs
Description
You are given a rooted tree with n vertices. The vertices are numbered from 1 to n, the root is the vertex number 1.
Each vertex has a color, let‘s denote the color of vertex v by cv. Initially cv = 0.
You have to color the tree into the given colors using the smallest possible number of steps. On each step you can choose a vertex v and a color x, and then color all vectices in the subtree of v (including v itself) in color x. In other words, for every vertex u, such that the path from root to u passes through v, set cu = x.
It is guaranteed that you have to color each vertex in a color different from 0.
You can learn what a rooted tree is using the link: https://en.wikipedia.org/wiki/Tree_(graph_theory).
Input
The first line contains a single integer n (2 ≤ n ≤ 104) — the number of vertices in the tree.
The second line contains n - 1 integers p2, p3, ..., pn (1 ≤ pi < i), where pi means that there is an edge between vertices i and pi.
The third line contains n integers c1, c2, ..., cn (1 ≤ ci ≤ n), where ci is the color you should color the i-th vertex into.
It is guaranteed that the given graph is a tree.
Output
Print a single integer — the minimum number of steps you have to perform to color the tree into given colors.
Sample Input
6
1 2 2 1 5
2 1 1 1 1 1
3
7
1 1 2 3 1 4
3 3 1 1 1 2 3
5
Hint
The tree from the first sample is shown on the picture (numbers are vetices‘ indices):
On first step we color all vertices in the subtree of vertex 1 into color 2 (numbers are colors):
On seond step we color all vertices in the subtree of vertex 5 into color 1:
On third step we color all vertices in the subtree of vertex 2 into color 1:
The tree from the second sample is shown on the picture (numbers are vetices‘ indices):
On first step we color all vertices in the subtree of vertex 1 into color 3 (numbers are colors):
On second step we color all vertices in the subtree of vertex 3 into color 1:
On third step we color all vertices in the subtree of vertex 6 into color 2:
On fourth step we color all vertices in the subtree of vertex 4 into color 1:
On fith step we color all vertices in the subtree of vertex 7 into color 3:
例如：1 2 2 1 5
代表：节点2和节点1相连，节点3和节点2相连，节点4和节点2相连，节点5和节点1相连，节点6和节点5相连。
第三行内容是需要将各个点涂成的颜色，给这个树涂色，有这么一条原则就是给某一节点涂色，以其为根节点的子树也将变为相应的颜色，我们可以成为一种颜料的溢出，问你最终需要
最少需要涂多少次颜色就可以满足题目要求。
解题思路：我们可以这样来思考，因为最后需要使所有的点都涂成要求的颜色，一定是按照从根节点到叶子节点遍历的涂色，但所有的点都遍历会造成浪费，我们只需要找出需要涂的点即可，
那么哪些点需要涂呢？我们发现只有那些最后要求的其父亲节点和本身不同色的需要涂色，因为需要向下改变自身颜色，那么只需要统计这样点的个数即可。
1 #include<cstdio> 2 #include<cstring> 3 #include<algorithm> 4 using namespace std; 5 int pr[10010]; 6 int a[10010]; 7 int main() 8 { 9 int n,i,counts; 10 scanf("%d",&n); 11 counts=0; 12 pr[0]=1; 13 pr[1]=1;///根节点的父亲节点是自身 14 for(i=2;i<=n;i++) 15 { 16 scanf("%d",&pr[i]); 17 } 18 for(i=1;i<=n;i++) 19 { 20 scanf("%d",&a[i]); 21 } 22 for(i=1;i<=n;i++) 23 { 24 if(a[i]!=a[pr[i]])///父亲节点和自身颜色不同 25 { 26 counts++; 27 } 28 } 29 printf("%d\n",counts); 30 return 0; 31 }
标签：tps ever scan sample 自身 dice c11 not tabs
原文地址：https://www.cnblogs.com/wkfvawl/p/9495233.html
