【图论】[NOIP2014]联合权值

题目

做完之后感觉 这个题应该是需要一些数学思想
题解看这个博客:链接

代码如下

#include<iostream>
#include<cstdio>
#include<cctype>

    using namespace std;
    #define in = read();
    typedef long long ll;
    typedef unsigned int ui;
    const ll size = 1000000 + 10000;

        struct point{   ll next,to,dis;}edge[size];

            ui n;
            ui a[size];
            ui site,ans,maxans;
            ui head[size];

inline ll read(){
        ll num = 0 , f = 1;    char ch = getchar();

        while(!isdigit(ch)){
                if(ch == '-')   f = -1;
                ch = getchar();
        }
        while(isdigit(ch)){
                num = num*10 + ch - '0';
                ch = getchar();
        }

        return num*f;
}

inline void add(ll x,ll y){
        edge[++site].next = head[x];
        edge[site].to = y;
        head[x] = site;
}

int main(){
        n in;
        for(int i=1;i<n;i++){
                ui x,y;   x in;   y in;
                add(x,y);   add(y,x);
        }
        for(int i=1;i<=n;i++){
                a[i] in;    a[i] %= 10007;
        }

        for(register int i=1;i<=n;i++){
                ll sum = 0;   ui max1= 0 , max2 = 0;
                for(register int j=head[i];j;j=edge[j].next){
                        if(a[edge[j].to] > max1){
                                max2 = max1;
                                max1 = a[edge[j].to];
                        }
                        else if(a[edge[j].to] > max2)
                                max2 = a[edge[j].to];
                        ans = (ans + sum*a[edge[j].to])%10007;
                        sum = (sum + a[edge[j].to])%10007;
                        maxans = max(maxans , max1*max2);
                }
        }

        ans = (ans*2)%10007;
        printf("%d %d",maxans,ans);
}


//COYG