OJ 1253 ordering problem

describe

PKU network laboratory often has activities that need to be bought out , However, the maximum amount of reimbursement expenses for each call out is C element , Yes N Grow vegetables and order , After a long order , Web lab for every dish i There is a quantitative evaluation score （ It means how delicious this dish is ）, by Vi, The price of each dish is Pi, Ask how to choose a variety of dishes , So that the total evaluation score of the dishes ordered can be maximized within the reimbursement limit .
    Be careful ： Due to the need for nutritional diversity , Each dish can only be ordered once .

Input
The first line of input has two integers C（1 <= C <= 1000） and N（1 <= N <= 100）,C Represents the total amount that can be reimbursed ,N> Represents the number of dishes you can order . Next N Each line consists of two in 1 To 100 Between （ Include 1 and 100） The whole number of , They represent the of the dish > Price and evaluation score of dishes .

Output
The output consists of only one line , This line contains only one integer , Means within the reimbursement limit , The maximum evaluation score of the dish ordered .

sample input 1 

1 3
1 5
3 3
2 5
24 8
2 9
8 6
4 1
1 4
2 2
10 5
2 1
1 4
sample output 1

5
30

The topic requires to find out the maximum order value , Dynamic programming can be used , Select a value and recurse it .

#include <iostream>
#include <bits/stdc++.h>
using namespace std;

int a[100],b[100],dp[1001];
int main()
{
    int c,n;
    while(cin>>c>>n)
    {
        memset(dp,0,sizeof(dp));
        for(int i=0;i<n;i++)
            cin>>a[i]>>b[i];
        for(int i=0;i<n;i++)
        {
            for(int j=c;j>=a[i];j--)
                dp[j]=max(dp[j],dp[j-a[i]]+b[i]);
        }
        cout<<dp[c]<<endl;
    }
    return 0;
}