POJ 1984

#include <cstdio> 
#include <iostream> 
#include <cstring>  
#include <cctype>  
#include <algorithm>  
#define LL unsigned __int64
using namespace std; 

const int N=  40100;

int pre[N],rank[N];
struct Edge{
	int u,v,c;
	char dir;
}edge[N];
struct Quest{
	int u,v;
	int index,idp;
	bool operator <(const Quest &a)const{
		if(index<a.index) return true;
		return false;
	}
}qask[N/4];
struct Node{
	int dx,dy;
}node[N];
int ans[N];
int n,m,qk;

int findx(int x){
    int r=x;
    int tx=node[x].dx,ty=node[x].dy;
    while(pre[r]!=-1){
	    r=pre[r];
	    tx+=node[r].dx;
	    ty+=node[r].dy;
    }
    int dtx,dty,q;
    while(x!=r){
	    q=pre[x];
	    dtx=node[x].dx,dty=node[x].dy;
	    node[x].dx=tx,node[x].dy=ty;
	    pre[x]=r;
	    tx-=dtx,ty-=dty;
    	x=q;
    }
	return r;   
}

void Union(int u,int v,int k){
	int uf=findx(u);
	int vf=findx(v);
	pre[uf]=vf;
	node[uf].dx=node[v].dx-node[u].dx;
	node[uf].dy=node[v].dy-node[u].dy;
	switch(edge[k].dir){
		case ‘N‘:node[uf].dy+=edge[k].c; break;
		case ‘S‘:node[uf].dy-=edge[k].c; break;
		case ‘W‘:node[uf].dx+=edge[k].c; break;
		case ‘E‘:node[uf].dx-=edge[k].c; break;
	}
}

void work(){
	int li=0,root1,root2;
	for(int i=0;i<qk;i++){
		for(int k=li;k<qask[i].index&&k<m;k++){
			Union(edge[k].u,edge[k].v,k);
		}
		root1=findx(qask[i].u);
		root2=findx(qask[i].v);
		if(root1!=root2){
			ans[qask[i].idp]=-1;
		}
		else {
			int a=abs(node[qask[i].u].dx-node[qask[i].v].dx);
			int b=abs(node[qask[i].u].dy-node[qask[i].v].dy);
			ans[qask[i].idp]=a+b;
		}
		li=qask[i].index;
	}
}

int main(){
	while(scanf("%d%d",&n,&m)!=EOF){
		for(int i=1;i<=n;i++){
			pre[i]=-1;
			node[i].dx=node[i].dy=0;
		}
		for(int i=0;i<m;i++){
			scanf("%d %d %d %c",&edge[i].u,&edge[i].v,&edge[i].c,&edge[i].dir);
		}
		scanf("%d",&qk);
		for(int i=0;i<qk;i++){
			scanf("%d%d%d",&qask[i].u,&qask[i].v,&qask[i].index);
			qask[i].idp=i;
		}
		sort(qask,qask+qk);
		work();
		for(int i=0;i<qk;i++)
		printf("%d\n",ans[i]);
	}
	return 0;
}