hihocoder 第二十九周 堆优化的Prim算法

又深刻理解了一遍prim和dijkstra算法，感觉蛮棒的~

第一次自己用邻接表写，just soso~ 啊哈~

一开始被优先队列，重载运算符给卡住了~ 蛋疼~

 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<stdlib.h>

13 #include<vector>

14 #define INF 1e7

15 #define MAXN 111111

16 using namespace std;

17 

18 

19 struct node{

20     int v, w;

21     bool operator < (const node& a) const {

22         return w > a.w;

23     }

24 };

25 

26 vector<node> G[MAXN];

27 bool vis[MAXN];

28 int dis[MAXN];

29 int n, m;

30 priority_queue<node> q;

31 

32 

33 void Prim(node s)

34 {

35     memset(vis, 0, sizeof(vis));

36     for (int i = 0; i <= n; ++i) dis[i] = INF;

37     while (!q.empty())  q.pop();

38     int ans = 0;

39     q.push(s);

40     while (!q.empty()) {

41         node u = q.top();

42         q.pop();

43         if (vis[u.v]) continue;

44         vis[u.v] = true;

45         ans += u.w;

46         //cout << ans << endl;

47         for (int i = 0; i < G[u.v].size(); ++i) {

48             int v = G[u.v][i].v;

49             if (!vis[v] && dis[v] > G[u.v][i].w) {

50                 dis[v] = G[u.v][i].w;

51                 q.push({ v, dis[v] });

52             }

53         }

54     }

55     cout << ans << endl;

56 }

57 

58 

59 int main()

60 {

61     int a, b, c;

62     cin >> n >> m;

63     for (int i = 1; i <= m; ++i) {

64         cin >> a >> b >> c;

65         G[a].push_back({ b, c });

66         G[b].push_back({ a, c });

67     }

68     Prim({ 1, 0 });

69     //system("pause");

70     return 0;

71 }