标签:cto ring stack get scanf ios queue 传送门 type
分析
经典的树型DP
我们记录dp[i][0/1]表示i的子树中到i的长度分别为偶数和奇数的长度和
dp2[i][0/1]则表示不在i的子树中的点到i的长度分别为偶数和奇数的长度和
然后根据边的长度情况转移一下就可以了
代码
#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
#include<cctype>
#include<cmath>
#include<cstdlib>
#include<queue>
#include<ctime>
#include<vector>
#include<set>
#include<map>
#include<stack>
using namespace std;
long long dp[100100][2],dp2[100100][2];
int sum[100100][2],sum2[100100][2];
int val[200200],to[200200],head[200200];
int nxt[200200],cnt,n,m;
inline void add(int x,int y,int z){
nxt[++cnt]=head[x];
head[x]=cnt;
to[cnt]=y;
val[cnt]=z;
nxt[++cnt]=head[y];
head[y]=cnt;
to[cnt]=x;
val[cnt]=z;
}
inline void dfs1(int x,int fa){
int i,j,k;
for(i=head[x];i;i=nxt[i]){
if(to[i]==fa)continue;
dfs1(to[i],x);
if(val[i]%2){
dp[x][0]+=dp[to[i]][1];
dp[x][0]+=1ll*sum[to[i]][1]*val[i];
sum[x][0]+=sum[to[i]][1];
dp[x][1]+=dp[to[i]][0]+1ll*val[i];
dp[x][1]+=1ll*sum[to[i]][0]*val[i];
sum[x][1]+=sum[to[i]][0]+1;
}else {
dp[x][0]+=dp[to[i]][0]+1ll*val[i];
dp[x][0]+=1ll*sum[to[i]][0]*val[i];
sum[x][0]+=sum[to[i]][0]+1;
dp[x][1]+=dp[to[i]][1];
dp[x][1]+=1ll*sum[to[i]][1]*val[i];
sum[x][1]+=sum[to[i]][1];
}
}
return;
}
inline void dfs2(int x,int fa){
int i,j,k;
long long t0=0,t1=0;
int s0=0,s1=0;
for(i=head[x];i;i=nxt[i]){
if(to[i]==fa)continue;
if(val[i]%2){
t0+=dp[to[i]][1];
t0+=1ll*sum[to[i]][1]*val[i];
s0+=sum[to[i]][1];
t1+=dp[to[i]][0]+1ll*val[i];
t1+=1ll*sum[to[i]][0]*val[i];
s1+=sum[to[i]][0]+1;
}else {
t0+=dp[to[i]][0]+1ll*val[i];
t0+=1ll*sum[to[i]][0]*val[i];
s0+=sum[to[i]][0]+1;
t1+=dp[to[i]][1];
t1+=1ll*sum[to[i]][1]*val[i];
s1+=sum[to[i]][1];
}
}
for(i=head[x];i;i=nxt[i]){
if(to[i]==fa)continue;
long long T0=t0,T1=t1;int S0=s0,S1=s1;
if(val[i]%2){
T0-=dp[to[i]][1];
T0-=1ll*sum[to[i]][1]*val[i];
S0-=sum[to[i]][1];
T1-=dp[to[i]][0]+1ll*val[i];
T1-=1ll*sum[to[i]][0]*val[i];
S1-=sum[to[i]][0]+1;
dp2[to[i]][0]+=dp2[x][1]+T1;
dp2[to[i]][0]+=1ll*(sum2[x][1]+S1)*val[i];
sum2[to[i]][0]+=sum2[x][1]+S1;
dp2[to[i]][1]+=dp2[x][0]+1ll*val[i]+T0;
dp2[to[i]][1]+=1ll*(sum2[x][0]+S0)*val[i];
sum2[to[i]][1]+=sum2[x][0]+1+S0;
dfs2(to[i],x);
}else {
T0-=dp[to[i]][0]+1ll*val[i];
T0-=1ll*sum[to[i]][0]*val[i];
S0-=sum[to[i]][0]+1;
T1-=dp[to[i]][1];
T1-=1ll*sum[to[i]][1]*val[i];
S1-=sum[to[i]][1];
dp2[to[i]][0]+=dp2[x][0]+1ll*val[i]+T0;
dp2[to[i]][0]+=1ll*(sum2[x][0]+S0)*val[i];
sum2[to[i]][0]+=sum2[x][0]+1+S0;
dp2[to[i]][1]+=dp2[x][1]+T1;
dp2[to[i]][1]+=1ll*(sum2[x][1]+S1)*val[i];
sum2[to[i]][1]+=sum2[x][1]+S1;
dfs2(to[i],x);
}
}
return;
}
int main(){
int i,j,k,x,y,z;
scanf("%d%d",&n,&m);
for(i=1;i<n;i++){
scanf("%d%d%d",&x,&y,&z);
add(x,y,z);
}
dfs1(1,0);
dfs2(1,0);
for(i=1;i<=m;i++){
scanf("%d",&x);
printf("%lld %lld\n",dp[x][1]+dp2[x][1],dp[x][0]+dp2[x][0]);
}
return 0;
}
标签:cto ring stack get scanf ios queue 传送门 type
原文地址:https://www.cnblogs.com/yzxverygood/p/9901946.html