洛谷P1111修复公路
思路：并查集
1 #include<cstdio> 2 #include<iostream> 3 #include<algorithm> 4 #include<math.h> 5 #include<vector> 6 #include<set> 7 using namespace std; 8 9 int f[1005] = { 0 }; 10 11 int find(int x) { return f[x] == x ? x : f[x] = find(f[x]); } 12 void merge(int i, int j) { f[find(i)] = find(j); } 13 14 bool judge(int n) { //判断所有村庄是否连通 15 int x = find(0); 16 for (int i = 0; i < n; i++) { 17 if (find(f[i]) != x) return false; 18 } 19 return true; 20 } 21 struct road { 22 int a, b, c; 23 }x[100005]; 24 struct cmp { //自定义multiset容器排序规则(升序) 25 bool operator()(const road& a, const road& b) const{ 26 return a.c < b.c || a.c == b.c; 27 } 28 }; 29 int main() { 30 int n, m; 31 bool fx = false; 32 multiset<road,cmp>h; 33 scanf("%d %d", &n, &m); 34 for (int i = 0; i < n; i++) f[i] = i; //初始化 35 for (int i = 0; i < m; i++) { 36 scanf("%d %d %d", &x[i].a, &x[i].b,&x[i].c); 37 h.insert(x[i]); 38 } 39 for (multiset<road>::iterator it = h.begin(); it != h.end(); it++) { 40 //printf("%d %d %d\n",(*it).a, (*it).b, (*it).c); 41 merge((*it).a, (*it).b); 42 if (judge(n)) { 43 printf("%d", (*it).c); 44 fx = true; 45 break; 46 } 47 } 48 if(!fx) printf("-1"); 49 return 0; 50 }
