bzoj4472

Posted 2020-11-07 せみしぐれ

初始时将1的限制赋为无穷大，然后对每个节点贪心，从大往小取，知道能取得的元素的最大值小于0

比较唯一性时注意下

#include<cstdio>
#include<cctype>
#include<algorithm>
#define maxn 100002
using namespace std;
bool vis[maxn];
int n,f[maxn],cnt,tmp[maxn],head[maxn],to[maxn<<1],nex[maxn<<1],inc[maxn],lim[maxn];
void read(int &x){
    char ch=getchar();x=0;int f=1;
    while(!isdigit(ch)){if(ch==‘-‘)f=-1;ch=getchar();}
    while(isdigit(ch)){x=(x<<1)+(x<<3)+ch-‘0‘;ch=getchar();}
    x*=f;
}
void addedge(int u,int v){to[++cnt]=v;nex[cnt]=head[u];head[u]=cnt;}
bool cmp1(int a,int b){return f[a]>f[b];}
void dfs(int now,int fa){
    f[now]=inc[now];
    for(int i=head[now];i;i=nex[i])if(to[i]!=fa)dfs(to[i],now);
    int hd=0,tail=0;
    for(int i=head[now];i;i=nex[i])if(to[i]!=fa)tmp[++tail]=to[i];
    sort(tmp+1,tmp+tail+1,cmp1);
    while(hd<min(lim[now]-1,tail) && f[tmp[hd+1]]>=0)f[now]+=f[tmp[++hd]],vis[now]|=vis[tmp[hd]];
    if(hd<tail && hd>0 && f[tmp[hd]]==f[tmp[hd+1]] || f[tmp[hd]]==0 && hd>0) vis[now]=1;
}

int main(){
    read(n);
    int x,y;
    for(int i=2;i<=n;i++)read(inc[i]);
    for(int i=2;i<=n;i++)read(lim[i]);lim[1]=1e9;
    for(int i=1;i<n;i++){read(x);read(y);addedge(x,y);addedge(y,x);}
    dfs(1,0);
    printf("%d\n",f[1]);
    if(vis[1])printf("solution is not unique");else printf("solution is unique");
}