CodeForces 367B Sereja ans Anagrams （map）

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题目地址：点击打开链接

题意：给定n个元素的序列a[]和m个元素的序列b[]，让你找到一个q使得a[q]、a[q+p]、…a[q+(m-1)*p]构成序列b。问你所有的q。

思路：i、i+p、i+2*p肯定构成一条长链，枚举链的起点，用map维护并判断长度为m的链与b序列是否相同。

map可以直接用==判断是否相等，涨姿势了

代码：

#include<bits/stdc++.h>using namespace std;typedef long long ll;const int maxn = 2e5+5;int a[maxn], b[maxn], ans[maxn];ll n, m, p;int main(void){    while(cin >> n >> m >> p)    {        for(int i = 1; i <= n; i++)            scanf("%d", &a[i]);        map<int, int> M;        for(int i = 1; i <= m; i++)            scanf("%d", &b[i]), M[b[i]]++;        map<int, int> ma;        int index = 0;        for(int i = 1; i <= p; i++)        {            ma.clear();            for(ll j = 0; j <= (m-1) && i+j*p <= n; j++)                ma[a[i+j*p]]++;            if(ma == M) ans[index++] = i;            for(ll j = m; i+j*p <= n; j++)            {                int pre = a[i+(j-m)*p];                if(ma[pre] == 1) ma.erase(pre);                else ma[pre]--;                ma[a[i+j*p]]++;                if(ma == M) ans[index++] = i+(j-m+1)*p;            }        }        printf("%d\n", index);        sort(ans, ans+index);        for(int i = 0; i < index; i++)            printf("%d%c", ans[i], i==index-1 ? '\n' : ' ');    }    return 0;}

Sereja has two sequences a and b and number p. Sequence a consists of n integers a1, a2, ..., an. Similarly, sequence b consists of mintegers b1, b2, ..., bm. As usual, Sereja studies the sequences he has. Today he wants to find the number of positions q(q + (m - 1)·p ≤ n; q ≥ 1), such that sequence b can be obtained from sequence aq, aq + p, aq + 2p, ..., aq + (m - 1)p by rearranging elements.

Sereja needs to rush to the gym, so he asked to find all the described positions of q.

Input

The first line contains three integers n, m and p (1 ≤ n, m ≤ 2·105, 1 ≤ p ≤ 2·105). The next line contains n integers a1, a2, ..., an(1 ≤ ai ≤ 109). The next line contains m integers b1, b2, ..., bm (1 ≤ bi ≤ 109).

Output

In the first line print the number of valid qs. In the second line, print the valid values in the increasing order.

Examples
input
5 3 11 2 3 2 11 2 3
output
21 3
input
6 3 21 3 2 2 3 11 2 3
output
21 2

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