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| #include <iostream>
#include<queue>
#include<string.h>
#include<stdio.h>
#define max(a,b) (a>b?a:b)
#define min(a,b) (a<b?a:b)
using namespace std;
struct node{
int v;
node* next;
node(int vv){
v = vv;
next = NULL;
}
};
const int N = 100000+5;
node *t ;
void add(node** h,node* p){
t = *h;
*h = p;
p->next = t;
}
node* head1[N];
node* head2[N];
int a[N],b[N];
bool vis1[N];
bool vis2[N];
int spfa(int s,int n){
queue<int> q;
int v;
memset(vis1,false,sizeof(vis1));
vis1[s] = true;
q.push(s);
while(!q.empty()){
int x = q.front();q.pop();
for(node* p=head1[x];p;p=p->next){
v = p->v;
a[v]=min(a[v],a[x]);
if(!vis1[v]){
q.push(v);
vis1[v] = true;
}
}
}
memset(vis2,false,sizeof(vis2));
vis2[n] = true;
q.push(n);
while(!q.empty()){
int x = q.front();q.pop();
for(node* p=head2[x];p;p=p->next){
v = p->v;
b[v]=max(b[v],b[x]);
if(!vis2[v]){
q.push(v);
vis2[v] = true;
}
}
}
int ans =0;
for(int i=1;i<=n;i++){
if(vis1[i] && vis2[i]) ans = max(ans,b[i]-a[i]);
}
return ans;
}
int main(int argc, char** argv) {
int n,m;
int u,v,c;
while(~scanf("%d%d",&n,&m)){
for(int i=1;i<=n;i++){
scanf("%d",&a[i]);
b[i] = a[i];
head1[i] = NULL;
head2[i] = NULL;
}
while(m--){
scanf("%d%d%d",&u,&v,&c);
add(&head1[u],new node(v));
add(&head2[v],new node(u));
if(c==2){
add(&head1[v],new node(u));
add(&head2[u],new node(v));
}
}
printf("%d\n",spfa(1,n));
}
return 0;
}
|