hdu1754I Hate It

http://acm.hdu.edu.cn/showproblem.php?pid=1754

依次比较左右子节点 父节点存最大值

View Code

 1  #include <iostream>

 2  #include<cstdio>

 3  #include<string.h>

 4  #define MAX 200000

 5  using namespace std;

 6  int s[MAX*4],a;

 7  void push(int w)

 8  {

 9      if(s[2*w]>s[2*w+1])

10      s[w] = s[2*w];

11      else

12      s[w] = s[2*w+1];

13  }

14  void build(int l,int r,int w)

15  {

16      if(l==r)

17      {

18          scanf("%d",&a);

19          s[w] = a;

20          return ;

21      }

22      int m = (l+r)/2;

23      build(l,m,2*w);

24      build(m+1,r,2*w+1);

25      push(w);

26  }

27  void add(int p,int da,int l,int r,int w)

28  {

29      if(l==r)

30      {

31          s[w] = da;

32          return;

33      }

34      int m = (l+r)/2;

35      if(p<=m)

36      add(p,da,l,m,2*w);

37      else

38      add(p,da,m+1,r,2*w+1);

39      push(w);

40  }

41  int search(int a,int b,int l,int r,int w)

42  {

43      if(a<=l&&b>=r)

44      {

45         return s[w];

46      }

47      int m = (l+r)/2,re = 0;

48      if(a<=m)

49      re = max(re,search(a,b,l,m,2*w));

50      if(b>m)

51      re = max(re,search(a,b,m+1,r,2*w+1));

52      return re;

53  }

54  int main()

55  {

56      int i,j,k1,k2,n,m;

57      char c;

58      while(scanf("%d%d",&n,&m)!=EOF)

59      {

60          build(1,n,1);

61          while(m--)

62          {

63              scanf("%*c%c",&c);

64              if(c=='Q')

65              {

66                  scanf("%d %d",&k1,&k2);

67                  printf("%d\n",search(k1,k2,1,n,1));

68              }

69              else

70              {

71                  scanf("%d %d",&k1,&k2);

72                  add(k1,k2,1,n,1);

73              }

74          }

75      }

76      return 0;

77  }