hdu 5199 Gunner (Hash))

Problem Description

Long long ago, there is a gunner whose name is Jack. He likes to go hunting very much. One day he go to the grove. There are n birds and n trees. The i−th bird stands on the top of the i−th tree. The trees stand in straight line from left to the right. Every tree has its height. Jack stands on the left side of the left most tree. When Jack shots a bullet in height H to the right, the bird which stands in the tree with height H will falls. Jack will shot many times, he wants to know how many birds fall during each shot.
a bullet can hit many birds, as long as they stand on the top of the tree with height of H.

 

 

Input

There are multiple test cases (about 5), every case gives n,m in the first line, n indicates there are n trees and n birds, m means Jack will shot m times.
In the second line, there are n numbers h[1],h[2],h[3],…,h[n] which describes the height of the trees.
In the third line, there are m numbers q[1],q[2],q[3],…,q[m] which describes the height of the Jack’s shots.
Please process to the end of file.
[Technical Specification]
1≤n,m≤1000000(106)
1≤h[i],q[i]≤1000000000(109)
All inputs are integers.

 

 

Output

For each q[i], output an integer in a single line indicates the number of birds Jack shot down.

 

 

Sample Input

4 3

1 2 3 4

1 1 4

 

 

Sample Output

1

0

1

 

     题意：给n个鸟的高度，猎人射m次，给出每次的高度，问猎人每次能射到几个鸟。

     Hash题：每给一个鸟的高度，就给这个高度加1，输出时只要输出这高度对应的值就行了。

 

#include<cstdio>
#include<cstring>
#include<map>
using namespace std;
map<int,int>p;
int main()
{
    int n,m,a;
    while (~scanf("%d%d",&n,&m))
    {
        p.clear();
        while (n--)
        {
            scanf("%d",&a);
            p[a]++;
        }
        while (m--)
        {
            scanf("%d",&a);
            printf("%d\n",p[a]);
            p[a]=0;
        }
    }
}