https://vjudge.net/problem/POJ-2236
快4s过的，但是排行榜上很多1s内，不知道如何优化。。
1 #include<iostream> 2 #include<cstdio> 3 #include<queue> 4 #include<cstring> 5 #include<algorithm> 6 #include<cmath> 7 #include<stack> 8 #define lson l, m, rt<<1 9 #define rson m+1, r, rt<<1|1 10 #define IO ios::sync_with_stdio(false);cin.tie(0); 11 #define INF 0x3f3f3f3f 12 typedef unsigned long long ll; 13 using namespace std; 14 int n, num, d, s, t, pre[10010]; 15 char c; 16 typedef struct{ 17 int x, y; 18 }Node; 19 Node node[10010]; 20 int flag[10010]; 21 ll length(ll a, ll b) 22 { 23 return a*a+b*b; 24 } 25 int find(int x) 26 { 27 while(x != pre[x]){ 28 x = pre[x]; 29 } 30 return x; 31 } 32 void join(int k) 33 { 34 int tx = find(k); 35 pre[k] = tx;//优化 36 for(int i = 1; i <= n; i++){ 37 if(flag[i]&&i != k){ 38 ll tmp = length(node[k].x-node[i].x, node[k].y-node[i].y); 39 if(tmp<=d*d){//一开始直接pre[i]=tx然后wa了，一定要是把根接上去 40 int ty = find(i); 41 pre[i] = ty;//优化 42 if(tx != ty){ 43 pre[ty] = tx; 44 } 45 } 46 } 47 } 48 } 49 int main() 50 { 51 IO; 52 memset(flag, 0, sizeof(flag)); 53 cin >> n >> d; 54 for(int i = 1; i <= n; i++){ 55 pre[i] = i; 56 } 57 for(int i = 1; i <= n; i++){ 58 cin >> node[i].x >> node[i].y; 59 } 60 while(cin >> c){ 61 if(c == 'O'){ 62 cin >> num; 63 flag[num] = 1; 64 join(num); 65 } 66 else if(c == 'S'){ 67 cin >> s >> t; 68 int tx = find(s); 69 pre[s] = tx; 70 int ty = find(t); 71 pre[t] = ty; 72 if(tx == ty) cout << "SUCCESS" << endl; 73 else cout << "FAIL" << endl; 74 } 75 } 76 return 0; 77 }