POJ 2828 Buy Tickets 线段树

题目： http://poj.org/problem?id=2828

很巧妙的题，逆序插入线段树，这样元素不用移动。用二叉排序树也能过。

 1 #include <stdio.h>

 2 #include <string.h>

 3 

 4 const int MAXN = 200010;

 5 

 6 int pos[MAXN], val[MAXN], ans[MAXN];

 7 

 8 struct Tree_Node

 9 {

10     int left, right;

11     int num;

12 } tree[MAXN<<2];

13 

14 void build(int left, int right, int step)

15 {

16     tree[step].left = left;

17     tree[step].right = right;

18     tree[step].num = right - left + 1;

19     if(left == right)

20     {

21         return;

22     }

23     int mid = (left + right) >> 1;

24     build(left, mid, step<<1);

25     build(mid+1, right, step<<1|1);

26 }

27 

28 void insert(int posi, int vali, int step)

29 {

30     tree[step].num--;

31     if(tree[step].left == tree[step].right)

32     {

33         ans[tree[step].left] = vali;

34         return;

35     }

36     if(posi < tree[step<<1].num)

37         insert(posi, vali, step<<1);

38     else

39         insert(posi - tree[step<<1].num, vali, step<<1|1);

40 }

41 

42 int main()

43 {

44     int n;

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

46     {

47         build(0, n-1, 1);

48         for(int i = 0; i < n; i++)

49             scanf("%d %d", &pos[i], &val[i]);

50         for(int i = n-1; i >= 0; i--)

51             insert(pos[i], val[i], 1);

52         for(int i = 0; i < n-1; i++)

53             printf("%d ", ans[i]);

54         printf("%d\n", ans[n-1]);

55     }

56     return 0;

57 }

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