Codeforces Round #383 (Div. 1) B

就是01背包问题

先用并查集再用01背包

复杂度为nw

代码如下

#include<cstdio>#include<cstring>#include<iostream>#include<algorithm>#include<vector>using namespace std;const int maxn=1005;int dp[maxn],w[maxn],b[maxn],f[maxn];vector<int>group[maxn]; int Find(int x){if(f[x]==x)return x;return f[x]=Find(f[x]); } void unite(int x,int y){int xx=Find(x);      int yy=Find(y);    if(xx!=yy)  f[xx]=yy;}int main(){int n,m,W;scanf("%d %d %d",&n,&m,&W);for(int i=1;i<=n;i++)scanf("%d",&w[i]);for(int i=1;i<=n;i++)scanf("%d",&b[i]);for(int i=1;i<=n;i++)f[i]=i;for(int i=0;i<m;i++){int x,y;scanf("%d %d",&x,&y);unite(x,y);}for(int i=0;i<maxn;i++)group[i].clear();for(int i=1;i<=n;i++)    group[Find(i)].push_back(i);memset(dp,0,sizeof(dp));for(int i=1;i<=n;i++){if(Find(i)!=i)continue;for(int j=W;j>=0;j--){int sumw=0,sumb=0;for(int k=0;k<group[i].size();k++){sumw+=w[group[i][k]];sumb+=b[group[i][k]];if(j>=w[group[i][k]]){dp[j]=max(dp[j],dp[j-w[group[i][k]]]+b[group[i][k]]);}}if(j>=sumw)dp[j]=max(dp[j],dp[j-sumw]+sumb);}}printf("%d\n",dp[W]);return 0; }