【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