【乱搞】【随机】Codeforces Round #254 (Div. 2) - D. DZY Loves FFT

D. DZY Loves FFT

Source

http://codeforces.com/contest/445/problem/D

Description

DZY loves Fast Fourier Transformation, and he enjoys using it.

Fast Fourier Transformation is an algorithm used to calculate convolution. Specifically, if a, b and c are sequences with length n, which are indexed from 0 to n - 1, and

We can calculate c fast using Fast Fourier Transformation.

DZY made a little change on this formula. Now

To make things easier, a is a permutation of integers from 1 to n, and b is a sequence only containing 0 and 1. Given a and b, DZY needs your help to calculate c.

Because he is naughty, DZY provides a special way to get a and b. What you need is only three integers n, d, x. After getting them, use the code below to generate a and b.


//x is 64-bit variable;
function getNextX() {
x = (x * 37 + 10007) % 1000000007;
return x;
}
function initAB() {
for(i = 0; i < n; i = i + 1){
a[i] = i + 1;
}
for(i = 0; i < n; i = i + 1){
swap(a[i], a[getNextX() % (i + 1)]);
}
for(i = 0; i < n; i = i + 1){
if (i < d)
b[i] = 1;
else
b[i] = 0;
}
for(i = 0; i < n; i = i + 1){
swap(b[i], b[getNextX() % (i + 1)]);
}
}

Operation x % y denotes remainder after division x by y. Function swap(x, y) swaps two values x and y.

 

Input

The only line of input contains three space-separated integers n, d, x (1 ≤ d ≤ n ≤ 100000; 0 ≤ x ≤ 1000000006). Because DZY is naughty, x can't be equal to 27777500.

Output

Output n lines, the i-th line should contain an integer ci - 1.

Examples
Input
3 1 1
Output
1
3
2
Input
5 4 2
Output
2
2
4
5
5
Input
5 4 3
Output
5
5
5
5
4
Note

In the first sample, a is [1 3 2], b is [1 0 0], so c0 = max(1·1) = 1, c1 = max(1·0, 3·1) = 3, c2 = max(1·0, 3·0, 2·1) = 2.

In the second sample, a is [2 1 4 5 3], b is [1 1 1 0 1].

In the third sample, a is [5 2 1 4 3], b is [1 1 1 1 0].

 

Solution

从a[]和b[]的生成方式可以看出这两个序列是几乎随机的。

优先队列维护从a[0]到a[i]的前50大的数,每次从里面从大到小地找有没有元素对应的b是等于1的,若有那么就是答案,若没有的话那就暴力跑一次a[0]...a[i]。注意有时候序列b里会有很多0,导致很多位置都无法在第一步就找到答案,所以预处理出所有使得b[i] != 0的i,这样会大大减小暴力跑时的耗时。

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 
 4 typedef long long ll;
 5 ll n,d,x,a[100111],b[100111];
 6 priority_queue<pair<ll,int>> que;
 7 
 8 ll getNextX() {
 9     x = (x * 37 + 10007) % 1000000007;
10     return x;
11 }
12 void initAB() {
13     int i;
14     for(i = 0; i < n; i = i + 1){
15         a[i] = i + 1;
16     }
17     for(i = 0; i < n; i = i + 1){
18         swap(a[i], a[getNextX() % (i + 1)]);
19     }
20     for(i = 0; i < n; i = i + 1){
21         if (i < d)
22             b[i] = 1;
23         else
24             b[i] = 0;
25     }
26     for(i = 0; i < n; i = i + 1){
27         swap(b[i], b[getNextX() % (i + 1)]);
28     }
29 }
30 
31 int main(){
32     cin >> n >> d >> x;
33     initAB();
34     vector<int> vb;
35     for(int i = 0;i < n;++i) if(b[i]) vb.push_back(i);
36     for(int i = 0;i < n;++i){
37         que.push({a[i],i});
38         bool found = 0;
39         priority_queue<pair<ll,int>> tmp;
40         for(int j = 0;!que.empty() && j < 50;++j){
41             ll t = que.top().first;
42             int id = que.top().second;
43             if(!found && b[i-id]){
44                 printf("%lld\n",t);
45                 found = 1;
46             }
47             tmp.push(que.top());
48             que.pop();
49         }
50         if(!found){
51             ll ans = 0;
52             for(int j = 0;j < vb.size() && vb[j] <= i;++j)
53                 ans = max(ans,a[i-vb[j]]);
54             printf("%lld\n",ans);
55         }
56         que = tmp;
57     }
58 
59     return 0;
60 }

 

posted @ 2017-09-03 00:55  doub7e  阅读(209)  评论(0编辑  收藏  举报