E - Knapsack 2 （背包问题变种）

#include<bits/stdc++.h>
#define x first
#define y second
#define PB push_back
#define mst(x,a) memset(x,a,sizeof(x))
#define all(a) begin(a),end(a)
#define rep(x,l,u) for(ll x=l;x<u;x++)
#define rrep(x,l,u) for(ll x=l;x>=u;x--)
#define sz(x) x.size()
#define IOS ios::sync_with_stdio(false);cin.tie(0);
using namespace std;
typedef unsigned long long ull;
typedef pair<int,int> PII;
typedef pair<char,char> PCC;
typedef long long ll;
typedef pair<ll,ll> PLL;
const int N=105;
const int M=1e5+10;
const int INF=0x3f3f3f3f;
const int MOD=1e9+7;
int w[N],v[N],f[N][M];
void solve(){
    int n,W;cin>>n>>W;
    int mx=-1;
    rep(i,1,n+1) cin>>w[i]>>v[i],mx=max(mx,v[i]);
    f[0][0]=0;
    int bound=mx*n;
    rep(i,1,bound+1) f[0][i]=INF;
    rep(i,1,n+1){
        rep(j,0,bound+1){
            if(j<v[i]) f[i][j]=f[i-1][j];
            else f[i][j]=min(f[i-1][j],f[i-1][j-v[i]]+w[i]);
        }
    }
    ll ans=0;
    rep(i,0,bound+1) if(f[n][i]<=W) ans=max(ans,i);
    cout<<ans<<endl;
}
int main(){
    IOS;
    //freopen("test.txt", "r", stdin);
    //freopen("test.txt", "w", stdout);
    //int t;cin>>t;
    //while(t--)
        solve();
    return 0;
}