[SCOI2005]繁忙的都市
裸的最小生成树。
1 #include<cstdio> 2 #include<iostream> 3 #include<algorithm> 4 #include<cstring> 5 #include<cmath> 6 #include<cstdlib> 7 #include<vector> 8 #include<queue> 9 #include<stack> 10 #include<cctype> 11 using namespace std; 12 #define enter puts("") 13 #define space putchar(' ') 14 #define Mem(a) memset(a, 0, sizeof(a)) 15 typedef long long ll; 16 typedef double db; 17 const int INF = 0x3f3f3f3f; 18 const db eps = 1e-8; 19 const int maxn = 5e4 + 5; 20 inline ll read() 21 { 22 ll ans = 0; 23 char ch = getchar(), last = ' '; 24 while(!isdigit(ch)) {last = ch; ch = getchar();} 25 while(isdigit(ch)) {ans = ans * 10 + ch - '0'; ch = getchar();} 26 if(last == '-') ans = -ans; 27 return ans; 28 } 29 inline void write(ll x) 30 { 31 if(x < 0) putchar('-'), x = -x; 32 if(x >= 10) write(x / 10); 33 putchar(x % 10 + '0'); 34 } 35 36 int n, m; 37 struct Node 38 { 39 int x, y, w; 40 bool operator < (const Node& other)const 41 { 42 return w < other.w; 43 } 44 }t[maxn]; 45 46 int Max = 0, cnt = 0; 47 48 int p[maxn]; 49 void init() 50 { 51 for(int i = 1; i <= n; ++i) p[i] = i; 52 } 53 int Find(int x) 54 { 55 return x == p[x] ? x : p[x] = Find(p[x]); 56 } 57 58 int main() 59 { 60 n = read(); m = read(); 61 init(); 62 for(int i = 1; i <= m; ++i) {t[i].x = read(); t[i].y = read(); t[i].w = read();} 63 sort(t + 1, t + m + 1); 64 for(int i = 1; i <= m; ++i) 65 { 66 int px = Find(t[i].x), py = Find(t[i].y); 67 if(px != py) 68 { 69 p[px] = py; 70 cnt++; Max = t[i].w; 71 if(cnt == n - 1) break; 72 } 73 } 74 write(n - 1); space; write(Max); enter; 75 return 0; 76 }
