HDU 4001 To Miss Our Children Time (DAG上的DP，最長路)

有三種磚 ， 要摞成一個Skyscraper ，給出長寬高類似矩形嵌套的部分序關係，根據這個關係給建立DAG圖，不過這樣要注意一下當磚的類型是0的時候有可能出現環的情況

用並查集維護下就好

#include <cstdio>#include <cstring>#define  max(a,b) (a>b?a:b)typedef long long ll;const int maxn=1050;int n;ll a[maxn],b[maxn];int d[maxn];ll c[maxn];ll g[maxn][maxn];ll dis[maxn];int ring[maxn];int find (int x){    return ring[x]==x?x:ring[x]=find(ring[x]);}void build(){    memset (g , 0 , sizeof(g));    for (int i=0 ; i<n ; ++i)        ring[i]=i;    for (int i=0 ; i<n ; ++i)    {        for (int j=0 ; j<n ; ++j)        {            if(i==j)continue;            if(d[i]==0)//d=0            {                if(d[j]==0)if(a[i]==a[j] && b[i]==b[j])                {                    int fi=find(i);                    int fj=find(j);                    if(fi==fj)continue;                    //g[fi][fj]+=c[j];                    c[fi]+=c[j];                    ring[fj]=fi;                    continue;                }                if(a[i]>=a[j] && b[i]>=b[j])g[i][j]=c[i];            }            if(d[i]==1)            {                if(a[i]>=a[j] && b[i]>=b[j] && a[i]*b[i]>a[j]*b[j])g[i][j]=c[i];            }            if(d[i]==2)            {                if(a[i]>a[j] && b[i]>b[j])g[i][j]=c[i];            }        }    }}ll dp(int x){    if(dis[x]>0)return dis[x];    ll ans=c[x];    for (int i=0 ; i<n ; ++i)    {        if(ring[i]==i)        if(g[x][i])ans=max(ans,dp(i)+c[x]);        //if(g[i][x])ans=max(ans,dp(i)+g[i][x]);    }    //printf("d[%d]=%d\n",x,dis[x]=ans);    return dis[x]=ans;}void debug (){    puts("graph:");    for (int i=0 ; i<n ;  ++i)    {        for (int j=0 ; j<n ; ++j)        printf("%I64d  ",g[i][j]);        puts("");    }    puts("c:");    for (int i=0 ; i<n ; ++i)    printf("%I64d %d~~~ " ,c[i],ring[i]);    puts("");}int main (){    while (scanf("%d",&n),n)    {        for (int i=0 ; i<n ; ++i)        {            scanf("%I64d%I64d%I64d%d",a+i , b+i , c+i , d+i);            if(a[i]<b[i])a[i]^=b[i]^=a[i]^=b[i];        }        memset (dis , 0 , sizeof(dis));        build();        ll ans=0;        //debug();        for (int i=0 ; i<n ; ++i)        {            if(ring[i]==i)                dis[i]=dp(i);            ans=max(ans,dis[i]);        }        printf("%I64d\n",ans);    }    return 0;}

 

HDU 上的類似題1069

資料比較小 用floyd 或DP都行

#include <cstdio>#include <cstring>#include <algorithm>#define max(a,b) (a>b?a:b)#define min(a,b) (a<b?a:b)using namespace std;const int maxn=95;int dp[maxn];int n;int l[maxn],w[maxn],h[maxn];int pin[maxn];int I=0;bool cmp(int a,int b){    return l[a]>l[b] || (l[a]==l[b] && w[a]>w[b]);}int main (){    int a,b,c;    while (scanf("%d",&n),n)    {        for (int i=0 ; i<n ; ++i)        {            scanf("%d%d%d",&a,&b,&c);            l[i]=max(a,b);w[i]=min(a,b);dp[i]=h[i]=c;            l[i+n]=max(a,c);w[i+n]=min(a,c);dp[i+n]=h[i+n]=b;            l[i+n+n]=max(b,c);w[i+n+n]=min(b,c);dp[i+n+n]=h[i+n+n]=a;        }        int N=3*n;        for (int i=0 ; i<N ; ++i)            pin[i]=i;        sort (pin , pin+N , cmp);        int ans=0;        //for (int k=0 ; k<N ; ++k)        for (int i=0 ; i<N ; ++i)        {            for (int j=i+1 ; j<N ; ++j)            {                //if(i==j)continue;                if(l[pin[i]]>l[pin[j]] && w[pin[i]]>w[pin[j]])                    dp[pin[j]]=max(dp[pin[j]],dp[pin[i]]+h[pin[j]]);                ans=max(ans,dp[pin[j]]);            }        }        /*for (int i=0 ; i<N ; ++i)            printf("%d %d %d %d\n",l[i],w[i],h[i] , dp[i]);*/        printf("Case %d: maximum height = %d\n",++I,ans);    }    return 0;}