Hrbust 2310 Tree Painting（欧拉路径性质）

Tree PaintingTime Limit: 1000 MSMemory Limit: 131072 KTotal Submit: 42(22 users)Total Accepted: 19(16 users)Rating: Special Judge: NoDescriptionGive you a tree, can you draw the tree with minimum strokes without overlapping? Noted that it is ok if two strokes intersect at one point. Here we define a tree as a connected undirected graph with N points and N-1 edges.Input

The input data has several test cases. The first line contains a positive integer T (T<=20), indicates the number of test cases.

For each case:

The first line contains an integers N (2<=N<=10^5), indicates the number of points on the tree numbered from 1 to N.

Then follows N-1 lines, each line contains two integers Xi, Yi means an edge connected Xi and Yi (1<=Xi, Yi<=N).

OutputFor each test case, you should output one line with a number K means the minimum strokes to draw the tree.Sample Input

2

2

1 2

5

1 2

1 5

2 3

2 4

Sample Output

1

2

Source"尚学堂杯"哈尔滨理工大学第六届程序设计竞赛

题意：给出一颗N个点N-1条边的树，问至少能有几笔画出来

欧拉路径性质：每有两个度数为级数的顶点就存在一条欧拉路径

#include <bits/stdc++.h>using namespace std;int t, n;int a[100000 + 10];int main(){    scanf("%d", &t);    while(t--){        scanf("%d", &n);        memset(a, 0, sizeof(a));        for(int i = 1; i < n; i++){            int x, y;            scanf("%d%d", &x, &y);            a[x]++, a[y]++;        }        int ans = 0;        for(int i = 1; i <= n; i++){            if(a[i]&1) ans++;        }        printf("%d\n", ans>>1);    }}