题目链接：http://www.lydsy.com/JudgeOnline/problem.php?id=2761
裸平衡树，输出坑爹。使用Treap，800ms。
1 #include <iostream> 2 #include <cstdio> 3 #include <algorithm> 4 #include <cstring> 5 #define rep(i,l,r) for(int i=l; i<=r; i++) 6 #define clr(x,y) memset(x,y,sizeof(x)) 7 using namespace std; 8 const int INF = 0x3f3f3f3f; 9 const int maxn = 50010; 10 struct node{ 11 int v,l,r,rnd; 12 }t[maxn]; 13 int T,n,x,tot,root; 14 bool flag; 15 inline int read(){ 16 int ans = 0, f = 1; 17 char c = getchar(); 18 while (!isdigit(c)){ 19 if (c == '-') f = -1; 20 c = getchar(); 21 } 22 while (isdigit(c)){ 23 ans = ans * 10 + c - '0'; 24 c = getchar(); 25 } 26 return ans * f; 27 } 28 void rotl(int &w){ 29 int k = t[w].r; t[w].r = t[k].l; t[k].l = w; w = k; 30 } 31 void rotr(int &w){ 32 int k = t[w].l; t[w].l = t[k].r; t[k].r = w; w = k; 33 } 34 void insert(int x,int &w){ 35 if (!w){ 36 w = ++tot; t[w].v = x; 37 t[w].rnd = rand(); t[w].l = t[w].r = 0; return; 38 } 39 if (t[w].v == x){ 40 flag = 1; 41 return; 42 } 43 else if (x < t[w].v){ 44 insert(x,t[w].l); 45 if (t[t[w].l].rnd < t[w].rnd) rotr(w); 46 } 47 else{ 48 insert(x,t[w].r); 49 if (t[t[w].r].rnd < t[w].rnd) rotl(w); 50 } 51 } 52 void work(){ 53 n = read(); root = tot = 0; 54 flag = 0; x = read(); insert(x,root); if (!flag) printf("%d",x); 55 rep(i,2,n){ 56 flag = 0; x = read(); insert(x,root); 57 if (!flag) printf(" %d",x); 58 } 59 printf(" "); 60 } 61 int main(){ 62 T = read(); 63 while (T--) work(); 64 return 0; 65 }
2015.11.27 update: 用STL的set就能做而且代码奇短，真可谓水题也。25行936ms。
1 #include <cstdio> 2 #include <set> 3 #define rep(i,l,r) for(int i=l; i<=r; i++) 4 using namespace std; 5 int T,n,x; 6 set <int> s; 7 void work(){ 8 scanf("%d%d",&n,&x); 9 s.clear(); s.insert(x); printf("%d",x); 10 rep(i,2,n){ 11 scanf("%d",&x); 12 set <int> :: iterator itor; 13 itor = s.find(x); 14 if (itor == s.end()){ 15 printf(" %d",x); 16 s.insert(x); 17 } 18 } 19 printf(" "); 20 } 21 int main(){ 22 scanf("%d",&T); 23 while (T--) work(); 24 return 0; 25 }
据说用哈希表也能做，改天来看看……