HDU 1754 I Hate It (线段树)

简单的线段树，多余的就不解释了。

 1 #include<cstdio>

 2 #include<iostream>

 3 

 4 using namespace std;

 5 #define INF 0xffffff0

 6 #define max(a,b) (a>b?a:b)

 7 #define min(a,b) (a<b?a:b)

 8 struct Node

 9 {

10     int maxV;

11     int L, R;

12     int Mid()

13     {

14         return (L+R)/2;

15     }

16 }Tree[800010];

17 int maxV = 0;

18 void BuildTree(int root,int L,int R);

19 void Query(int root,int s,int e);

20 void Insert(int root,int i,int v);//第i个数 为 V

21 

22 int main()

23 {

24     int N, M;

25     while(scanf("%d%d",&N,&M) != EOF)

26     {

27         int k;

28         BuildTree(0,1,N);

29         for(int i = 1; i <= N; i++)

30         {

31             scanf("%d",&k);

32             Insert(0,i,k);

33         }

34         while(M--)

35         {

36             int s, e;

37             char str[2];

38             maxV = 0;

39             scanf("%s%d%d",str,&s,&e);

40             if(str[0] == 'Q')

41             {

42                 Query(0,s,e);

43                 printf("%d\n",maxV);

44             }

45             else

46                 Insert(0,s,e);

47         }

48     }

49     return 0;

50 }

51 

52 void BuildTree(int root,int L,int R)

53 {

54     Tree[root].L = L;

55     Tree[root].R = R;

56     Tree[root].maxV = 0;

57     if(L != R)

58     {

59         BuildTree(root*2+1,L,Tree[root].Mid());

60         BuildTree(root*2+2,Tree[root].Mid()+1,R);

61     }

62 }

63 void Query(int root,int s,int e)

64 {

65     if(Tree[root].maxV <= maxV)

66         return ;

67     if(Tree[root].L == s && Tree[root].R == e)

68     {

69         maxV = max(Tree[root].maxV, maxV);

70         return ;

71     }

72     if(e <= Tree[root].Mid())

73         Query(root*2+1,s, e);

74     else if( s > Tree[root].Mid())

75         Query(root*2+2,s, e);

76     else

77     {

78         Query(root*2+1,s,Tree[root].Mid());

79         Query(root*2+2,Tree[root].Mid()+1,e);

80     }

81 }

82 void Insert(int root,int i,int v)//第i个数 为 V

83 {

84     if(Tree[root].L == Tree[root].R)

85     {

86         Tree[root].maxV = v;

87         return ;

88     }

89     Tree[root].maxV = max(v,Tree[root].maxV);

90     if(i <= Tree[root].Mid())

91         Insert(root*2+1,i,v);

92     else

93         Insert(root*2+2,i,v);

94 }