由于只删除最小值和只查询最大值，所以我们只要维护一个maxn和一个size即可，需要注意的是删除到集合空时需要重新将maxn赋值为无穷小。
1 #include <iostream> 2 #include <cstring> 3 #include <cstdio> 4 using namespace std; 5 6 int main () 7 { 8 int n; 9 while ( scanf("%d", &n) != EOF ) 10 { 11 int op, tmp, maxn = -1111111111, size = 0; 12 for ( int i = 0; i < n; i++ ) 13 { 14 scanf("%d", &op); 15 if ( op == 1 ) 16 { 17 scanf("%d", &tmp); 18 size++; 19 if ( tmp > maxn ) maxn = tmp; 20 } 21 else if ( op == 2 ) 22 { 23 if ( size > 0 ) 24 { 25 size--; 26 if ( size == 0 ) maxn = -1111111111; 27 } 28 } 29 else 30 { 31 if ( size == 0 ) 32 { 33 printf("0 "); 34 } 35 else 36 { 37 printf("%d ", maxn); 38 } 39 } 40 } 41 } 42 return 0; 43 }
另外，别的平衡的数据结构也可以过，这里用的是Treap（主要是测模板），比赛推荐用multiset。
1 #include <iostream> 2 #include <cstring> 3 #include <cstdlib> 4 #include <cstdio> 5 using namespace std; 6 7 struct Node 8 { 9 Node * ch[2]; 10 int v, r, size; 11 int cmp( int x ) 12 { 13 if ( x == v ) return -1; 14 return x < v ? 0 : 1; 15 } 16 void maintain() 17 { 18 size = 1; 19 if ( ch[0] != NULL ) size += ch[0]->size; 20 if ( ch[1] != NULL ) size += ch[1]->size; 21 } 22 }; 23 24 Node * root; 25 26 void rotate( Node * & o, int d ) 27 { 28 Node * k = o->ch[d ^ 1]; 29 o->ch[d ^ 1] = k->ch[d]; 30 k->ch[d] = o; 31 o->maintain(); 32 k->maintain(); 33 o = k; 34 } 35 36 void insert( Node * & o, int x ) 37 { 38 if ( o == NULL ) 39 { 40 o = new Node(); 41 o->ch[0] = o->ch[1] = NULL; 42 o->v = x; 43 o->r = rand(); 44 o->size = 1; 45 } 46 else 47 { 48 int d = ( x <= o->v ? 0 : 1 ); 49 insert( o->ch[d], x ); 50 if ( o->ch[d]->r > o->r ) 51 { 52 rotate( o, d ^ 1 ); 53 } 54 else 55 { 56 o->maintain(); 57 } 58 } 59 } 60 61 void remove( Node * & o, int x ) 62 { 63 int d = o->cmp(x); 64 if ( d == -1 ) 65 { 66 if ( o->ch[0] != NULL && o->ch[1] != NULL ) 67 { 68 int dd = ( o->ch[0]->r > o->ch[1]->r ? 1 : 0 ); 69 rotate( o, dd ); 70 remove( o->ch[dd], x ); 71 } 72 else 73 { 74 Node * u = o; 75 if ( o->ch[0] == NULL ) o = o->ch[1]; 76 else o = o->ch[0]; 77 delete u; 78 } 79 } 80 else 81 { 82 remove( o->ch[d], x ); 83 } 84 if ( o != NULL ) o->maintain(); 85 } 86 87 int findm( Node * o, int d ) 88 { 89 while ( o->ch[d] != NULL ) o = o->ch[d]; 90 return o->v; 91 } 92 93 int main () 94 { 95 int n; 96 while ( scanf("%d", &n) != EOF ) 97 { 98 root = NULL; 99 for ( int i = 0; i < n; i++ ) 100 { 101 int op, x; 102 scanf("%d", &op); 103 if ( op == 1 ) 104 { 105 scanf("%d", &x); 106 insert( root, x ); 107 } 108 else if ( op == 2 ) 109 { 110 if ( root != NULL ) 111 { 112 x = findm( root, 0 ); 113 remove( root, x ); 114 } 115 } 116 else 117 { 118 if ( root == NULL ) 119 { 120 x = 0; 121 } 122 else 123 { 124 x = findm( root, 1 ); 125 } 126 printf("%d ", x); 127 } 128 } 129 } 130 return 0; 131 }