poj 1276 Cash Machine(多重背包)

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
#include<string>
#include<vector>
#include<stack>
#include<bitset>
#include<cstdlib>
#include<cmath>
#include<set>
#include<list>
#include<deque>
#include<map>
#include<time.h>
#include<queue>
#define ll long long int
using namespace std;
inline ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
inline ll lcm(ll a,ll b){return a/gcd(a,b)*b;}
int moth[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};
int dir[4][2]={1,0 ,0,1 ,-1,0 ,0,-1};
int dirs[8][2]={1,0 ,0,1 ,-1,0 ,0,-1, -1,-1 ,-1,1 ,1,-1 ,1,1};
const int inf=0x3f3f3f3f;
const ll mod=1000000007;
int a[15];
int value[15];
int dp[100007];
int main(){
    ios::sync_with_stdio(false);
    int mo;
    while(cin>>mo){
        memset(dp,0,sizeof(dp));
        int n;
        cin>>n;
        for(int i=1;i<=n;i++)
            cin>>a[i]>>value[i];
        dp[0]=1;
        for(int i=1;i<=n;i++){
            int temp=a[i]; int now=1;
            while(1){
                if(temp>now){
                    temp-=now;
                    for(int j=mo;j>=now*value[i];j--)
                        if(dp[j-now*value[i]])
                            dp[j]=1;
                    now*=2;
                }else{
                    for(int j=mo;j>=temp*value[i];j--)
                        if(dp[j-temp*value[i]])
                            dp[j]=1;
                        break;
                }
            }
        }
        int ans=0;
        for(int i=mo;i>=0;i--){
            if(dp[i]){
                ans=i; break;
            }
        }
        cout<<ans<<endl;
    }
    return 0;
}