hdu 3926 Hand in Hand

判断同构图。题意得好好理解一下。

因为每个结点最大度为二，则任意连通分支必为链或者环 。可以对所有结点进行排序比较。

  1 #include<iostream>

  2 #include<cstdio>

  3 #include<cstdlib>

  4 #include<cstring>

  5 #include<string>

  6 #include<queue>

  7 #include<algorithm>

  8 #include<map>

  9 #include<iomanip>

 10 #include<climits>

 11 #include<string.h>

 12 #include<cmath>

 13 #include<stdlib.h>

 14 #include<vector>

 15 #include<stack>

 16 #include<set>

 17 #define INF 1e7

 18 #define MAXN 10010

 19 #define maxn 1000010

 20 #define Mod 1000007

 21 #define N 1010

 22 using namespace std;

 23 typedef long long LL;

 24 

 25 struct graph{

 26     int son;

 27     bool ring;

 28 }g1[MAXN], g2[MAXN];

 29 int num1, num2;

 30 int fa1[MAXN], fa2[MAXN];

 31 

 32 void init()

 33 {

 34     for (int i = 0; i < MAXN; ++i) {

 35         fa1[i] = fa2[i] = i;

 36         g1[i].son = g2[i].son = 1;

 37         g1[i].ring = g2[i].ring = false;

 38     }

 39 }

 40 

 41 int findset(int x, int fa[])

 42 {

 43     return x == fa[x] ? x : findset(fa[x],fa);

 44 }

 45 

 46 void join(int x,int y,int fa[], graph g[])

 47 {

 48     int root1, root2;

 49     root1 = findset(x, fa);

 50     root2 = findset(y, fa);

 51     if (root1 == root2)

 52         g[root1].ring = true;

 53     else {

 54         if (g[root1].son >= g[root2].son) {

 55             fa[root2] = root1;

 56             g[root1].son += g[root2].son;

 57         }

 58         else {

 59             fa[root1] = root2;

 60             g[root2].son += g[root1].son;

 61         }

 62     }

 63 }

 64 

 65 bool cmb(const graph &g1, const graph &g2)//子结点优先+先链后环排序 

 66 {

 67     if (g1.son < g2.son) return true;

 68     else if (g1.son == g2.son && g1.ring < g2.ring)

 69         return true;

 70     return false;

 71 }

 72 

 73 

 74 bool cmp(int num, graph g1[], graph g2[]) //判断图是否同构

 75 {

 76     sort(g1 + 1, g1 + num + 1, cmb); //排序

 77     sort(g2 + 1, g2 + num + 1, cmb);

 78     for (int i = 1; i <= num; ++i)

 79         if (g1[i].son != g2[i].son || (g1[i].son == g2[i].son && g1[i].ring != g2[i].ring))

 80             return false;

 81     return true;

 82 }

 83 

 84 int main()

 85 {

 86     int kase, T = 0;

 87     int link1, link2;

 88     int hand1, hand2;

 89     int ans1, ans2;

 90     bool flag;

 91     scanf("%d",&kase);

 92     while (kase--) {

 93         flag = true;

 94         init();

 95         cin >> num1 >> link1;

 96         for (int i = 1; i <= link1; ++i) {

 97             cin >> hand1 >> hand2;

 98             join(hand1,hand2,fa1,g1);

 99         }

100         cin >> num2 >> link2;

101         if (link1 != link2) flag = false;

102         for (int i = 1; i <= link2; ++i) {

103             cin >> hand1 >> hand2;

104             if (flag == false) continue;

105             else join(hand1,hand2,fa2,g2);

106         }

107         flag = cmp(num2, g1, g2);

108         if (flag == false)

109             printf("Case #%d: NO\n", ++T);

110         else

111         {

112                 printf("Case #%d: YES\n", ++T);

113         }

114 

115     }

116     return 0;

117 }