[HDOJ1301]Jungle Roads
题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=1301
最小生成树 (Kruskal)
1 #pragma warning(disable:4996) 2 #include <algorithm> 3 #include <iostream> 4 #include <iomanip> 5 #include <cstring> 6 #include <climits> 7 #include <complex> 8 #include <fstream> 9 #include <cassert> 10 #include <cstdio> 11 #include <bitset> 12 #include <vector> 13 #include <deque> 14 #include <queue> 15 #include <stack> 16 #include <ctime> 17 #include <set> 18 #include <map> 19 #include <cmath> 20 21 using namespace std; 22 23 typedef struct Node { 24 int a; 25 int b; 26 int v; 27 friend bool operator < (Node a, Node b) { 28 return a.v > b.v; 29 } 30 }Node; 31 32 const int maxn = 20010; 33 int pre[maxn]; 34 int n, ans; 35 Node p; 36 priority_queue<Node> pq; 37 38 int find(int x) { 39 return x == pre[x] ? x : pre[x] = find(pre[x]); 40 } 41 42 bool unite(int x, int y) { 43 x = find(x); 44 y = find(y); 45 if (x != y) { 46 pre[y] = x; 47 return true; 48 } 49 return false; 50 } 51 inline void init() { 52 for (int i = 0; i < maxn; i++) { 53 pre[i] = i; 54 } 55 while (!pq.empty()) pq.pop(); 56 } 57 58 int main() { 59 // freopen("in", "r", stdin); 60 while (~scanf("%d", &n) && n) { 61 init(); 62 char a[2], b[2]; 63 int cnt = 0; 64 int m, v; 65 ans = 0; 66 n--; 67 for (int i = 0; i < n; i++) { 68 scanf("%s %d", &a, &m); 69 for (int i = 0; i < m; i++) { 70 scanf("%s %d", &b, &v); 71 p.a = a[0] - 'A'; 72 p.b = b[0] - 'A'; 73 p.v = v; 74 pq.push(p); 75 } 76 } 77 while (n) { 78 p = pq.top(); 79 pq.pop(); 80 if (unite(p.a, p.b)) { 81 n--; 82 ans += p.v; 83 } 84 } 85 printf("%d\n", ans); 86 } 87 }