poj 2828 BuyTickets（线段树+插队问题）

Buy Tickets

Time Limit: 4000MS Memory Limit: 65536KTotal Submissions: 21279 Accepted: 10426

Description

Railway tickets were difficult to buy around the Lunar New Year in China, so we must get up early and join a long queue…

The Lunar New Year was approaching, but unluckily the Little Cat still had schedules going here and there. Now, he had to travel by train to Mianyang, Sichuan Province for the winter camp selection of the national team of Olympiad in Informatics.

It was one o’clock a.m. and dark outside. Chill wind from the northwest did not scare off the people in the queue. The cold night gave the Little Cat a shiver. Why not find a problem to think about? That was none the less better than freezing to death!

People kept jumping the queue. Since it was too dark around, such moves would not be discovered even by the people adjacent to the queue-jumpers. “If every person in the queue is assigned an integral value and all the information about those who have jumped the queue and where they stand after queue-jumping is given, can I find out the final order of people in the queue?” Thought the Little Cat.

Input

There will be several test cases in the input. Each test case consists of N + 1 lines where N (1 ≤ N ≤ 200,000) is given in the first line of the test case. The next N lines contain the pairs of values Pos_i and Val_i in the increasing order of i (1 ≤ i ≤ N). For each i, the ranges and meanings of Pos_i and Val_i are as follows:

• Pos_i ∈ [0, i − 1] — The i-th person came to the queue and stood right behind the Pos_i-th person in the queue. The booking office was considered the 0th person and the person at the front of the queue was considered the first person in the queue.
• Val_i ∈ [0, 32767] — The i-th person was assigned the value Val_i.

There no blank lines between test cases. Proceed to the end of input.

Output

For each test cases, output a single line of space-separated integers which are the values of people in the order they stand in the queue.

Sample Input

40 771 511 332 6940 205231 192431 38900 31492

Sample Output

77 33 69 5131492 20523 3890 19243

Hint

The figure below shows how the Little Cat found out the final order of people in the queue described in the first test case of the sample input.

Source

POJ Monthly--2006.05.28, Zhu, Zeyuan

看了别人题解才做出来的。

用G++提交会超时，要用C++提交。

题解：

   线段树存的是剩余的位置数，如果剩余的位置数够，就递归左子树，不够就递归右子树。逆序插入，每次选的位置，都是他想要的位置。找到这个位置后，就可以看做把这个节点删了，从整个队伍中把这个位置给去除掉了。

#include<iostream>#include<algorithm>#include<cstdio>#include<cstring>#include<cmath>#include<string>const int MAX_N = 200010;int dat[MAX_N <<2];int pos[MAX_N];int val[MAX_N];int tmp[MAX_N];int sizea;int n;using namespace std;void init()//每个叶子节点剩余位子为1{int i;for (n = 1; n<sizea; n <<= 1);//找到叶子节点数for (i = n-1; i <=2*n; i++)//递推初始化{dat[i] = 1;}for (i = n - 2; i >= 0; i--){dat[i] = dat[2 * i + 1] + dat[2 * i + 2];}}void insert(int k, int pos, int val){if (k >= n - 1)//到了叶子节点{tmp[k-n+1] = val;//实际插入的位置dat[k] = 0;return;}if (dat[2 * k + 1] >= pos)insert(2 * k + 1, pos, val);//左边位置够else insert(2 * k + 2, pos-dat[2*k+1], val);dat[k]--;}int main(){int i;while (scanf("%d",&sizea)!=EOF){init();for (i = 0; i<sizea; i++)scanf("%d%d", &pos[i], &val[i]);for (i = sizea - 1; i >= 0; i--)//逆序插入insert(0, pos[i]+1, val[i]);for (i = 0; i<sizea; i++){if (i) printf(" ");printf("%d", tmp[i]);}printf("\n");}return 0;}