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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posted @ 2013-11-05 19:17  Anti-Magic  阅读(137)  评论(0)  编辑  收藏  举报