题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=1166
线段树节点更新练习
第三棵线段树……TUT……
1 #include <cstdio> 2 #include <cstring> 3 4 const int MAXN = 50000 + 10; 5 6 struct Node 7 { 8 int l, r; 9 int sum; 10 Node *l_child, *r_child; 11 }; 12 13 int N; 14 int cnt; 15 Node Tree[ MAXN + MAXN ]; 16 17 void BuildTree( int l, int r, Node *Td ) 18 { 19 Td -> l = l; 20 Td -> r = r; 21 22 if ( l == r ) 23 { 24 scanf( "%d", &Td->sum ); 25 return; 26 } 27 28 ++cnt; 29 Td-> l_child = Tree + cnt; 30 BuildTree( l, (l + r) / 2, Td -> l_child ); 31 32 ++cnt; 33 Td -> r_child = Tree + cnt; 34 BuildTree( (l + r) / 2 + 1, r, Td -> r_child ); 35 36 Td ->sum = Td -> l_child -> sum + Td -> r_child -> sum; 37 } 38 39 void Update( int ii, int &e, Node *Td, char &op ) 40 { 41 if ( ii == Td->l && ii == Td->r ) 42 { 43 if ( op == 'S' ) Td -> sum -= e; 44 else Td -> sum += e; 45 return; 46 } 47 48 int mid = ( Td->l + Td->r ) / 2; 49 if ( ii <= mid ) 50 Update( ii, e, Td->l_child, op ); 51 else if ( ii > mid ) 52 Update( ii, e, Td->r_child, op ); 53 54 Td -> sum = Td -> l_child -> sum + Td -> r_child -> sum; 55 return; 56 } 57 58 int Query( int l, int r, Node *Td ) 59 { 60 if ( Td -> l == l && Td -> r == r ) return Td->sum; 61 62 int mid = (Td->l + Td->r) / 2; 63 64 if ( r <= mid ) return Query( l, r, Td->l_child ); 65 else if ( l > mid ) return Query( l, r, Td->r_child ); 66 else return Query( l, mid, Td -> l_child ) + Query( mid + 1, r, Td -> r_child ); 67 } 68 69 70 int main() 71 { 72 int T, tt = 0; 73 char op[10]; 74 scanf("%d", &T ); 75 while ( T-- ) 76 { 77 cnt = 0; 78 scanf( "%d", &N ); 79 BuildTree( 1, N, Tree ); 80 printf("Case %d:\n", ++tt ); 81 while ( scanf( "%s", op ), op[0] != 'E' ) 82 { 83 int a, b; 84 scanf( "%d%d", &a, &b ); 85 switch( op[0] ) 86 { 87 case 'Q': 88 printf( "%d\n", Query(a, b, Tree) ); 89 break; 90 91 case 'S': 92 case 'A': 93 Update( a, b, Tree, op[0] ); 94 break; 95 } 96 } 97 } 98 return 0; 99 }