【poj1984】 Navigation Nightmare

// poj1984
#include<algorithm>
#include<iostream>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<cmath>
#define LL long long
#define MOD 100000000
#define inf 2147483640
#define Pi acos(-1.0)
#define free(a) freopen(a".in","r",stdin),freopen(a".out","w",stdout);
using namespace std;

const int maxn=100010;
struct edge {int u,v,w,t;}e[maxn];
struct data {int u,v,id,d;}t[maxn];
int n,m,q,X[maxn],Y[maxn],ans[maxn],fa[maxn];

bool cmp(data a,data b) {
	return a.id<b.id;
}
int find(int x) {
	if (x==fa[x]) return x;
	int f=find(fa[x]);
	X[x]+=X[fa[x]];
	Y[x]+=Y[fa[x]];
	return fa[x]=f;
}
int main() {
	scanf("%d%d",&n,&m);
	char ch;
	for (int x,u,v,w,i=1;i<=m;i++) {
		scanf("%d%d%d %c",&u,&v,&w,&ch);
		if (ch==‘N‘) x=0;else if (ch==‘S‘) x=1;else if (ch==‘W‘) x=2;else x=3;
		e[i]=(edge){u,v,w,x};
	}
	scanf("%d",&q);
	for (int i=1;i<=q;i++) scanf("%d%d%d",&t[i].u,&t[i].v,&t[i].id),t[i].d=i;
	sort(t+1,t+1+q,cmp);
	for (int i=1;i<=n;i++) fa[i]=i;
	int pp=1;
	for (int u,v,w,ty,i=1;i<=m;i++) {
		u=e[i].u,v=e[i].v,w=e[i].w,ty=e[i].t;
		int r1=find(u),r2=find(v);
		fa[r1]=v;
		if (ty==0) X[r1]-=X[u],Y[r1]=e[i].w-Y[u];
		else if (ty==1) X[r1]-=X[u],Y[r1]=-e[i].w-Y[u];
		else if (ty==2) X[r1]=-e[i].w-X[u],Y[r1]-=Y[u];
		else X[r1]=e[i].w-X[u],Y[r1]-=Y[u];
		while (t[pp].id==i && pp<=q) {
			if (find(t[pp].u)!=find(t[pp].v)) ans[t[pp].d]=-1;
			else ans[t[pp].d]=abs(X[t[pp].u]-X[t[pp].v])+abs(Y[t[pp].u]-Y[t[pp].v]);
			pp++;
		}
		if (pp==q+1) break;
	}
	for (int i=1;i<=q;i++) printf("%d\n",ans[i]);
	return 0;
}