HDU 1166 敌兵布阵

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 }