Codeforces Round #215 (Div. 2) -B. Sereja and Suffixes

B. Sereja and Suffixes

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

Sereja has an array a, consisting of n integers a₁, a₂, ..., a_n. The boy cannot sit and do nothing, he decided to study an array. Sereja took a piece of paper and wrote out m integers l₁, l₂, ..., l_m (1 ≤ l_i ≤ n). For each number l_i he wants to know how many distinct numbers are staying on the positions l_i, l_i + 1, ..., n. Formally, he want to find the number of distinct numbers among a_li, a_li + 1, ..., a_n.?

Sereja wrote out the necessary array elements but the array was so large and the boy was so pressed for time. Help him, find the answer for the described question for each l_i.

Input

The first line contains two integers n and m (1 ≤ n, m ≤ 10⁵). The second line contains n integers a₁, a₂, ..., a_n (1 ≤ a_i ≤ 10⁵) — the array elements.

Next m lines contain integers l₁, l₂, ..., l_m. The i-th line contains integer l_i (1 ≤ l_i ≤ n).

Output

Print m lines — on the i-th line print the answer to the number l_i.

Sample test(s)

Input

10 10
1 2 3 4 1 2 3 4 100000 99999
1
2
3
4
5
6
7
8
9
10

Output

6
6
6
6
6
5
4
3
2
1

            
題目是說，有一個數組a，有n個元素，然後進行m次詢問，位置爲p，找出每次詢問後，位置p後面有多少個不同的數字。

最先想到的是用集合解決，但是一開始方法比較笨：

#include<iostream>
#include<string.h>
#include<stdio.h>
#include<ctype.h>
#include<algorithm>
#include<stack>
#include<queue>
#include<set>
#include<math.h>
#include<vector>
#include<map>
#include<deque>
#include<list>
using namespace std;
int a[999999];
int main()
{
    int n,m,p;
    int i;
    set<int>s;
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        for(i=1; i<=n; i++)
            scanf("%d",&a[i]);
        for(i=1; i<=n; i++)
        {
            scanf("%d",&p);
            for(int j=p; j<=n; j++)
                s.insert(a[j]);
            printf("%d\n",s.size());
            s.clear();
        }
    }
    return 0；}

結果TLE，然後想到優化：從後往前找——

#include<iostream>
#include<string.h>
#include<stdio.h>
#include<ctype.h>
#include<algorithm>
#include<stack>
#include<queue>
#include<set>
#include<math.h>
#include<vector>
#include<map>
#include<deque>
#include<list>
using namespace std;
int a[999999];
int b[999999];
set<int>s;
int main()
{
    int n,m,p;
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        for(int i=1; i<=n; i++)
            scanf("%d",&a[i]);
        for(int i=n; i>=1; i--)
        {
            s.insert(a[i]);
            b[i]=s.size();
        }
        for(int i=0; i<m; i++)
        {
            scanf("%d",&p);
            printf("%d\n",b[p]);
        }
        s.clear();
    }
    return 0;
}