bzoj2015 [Usaco2010 Feb]Chocolate Giving（最短路裸题）

spfa版，复杂度O(m)

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>
#define N 50010
#define M 100010
#define inf 0x3f3f3f3f
inline int read(){
int x=0,f=1;char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9') x=x*10+ch-'0',ch=getchar();
return x*f;
}
int n,m,tt,h
,num=0,d
;
bool f
;
struct edge{
int to,next,val;
}data[M<<1];
void spfa(){
std::queue<int>q;
memset(d,0x3f,sizeof(d));
q.push(1);f[1]=1;d[1]=0;

128ea
while(!q.empty()){
int x=q.front();q.pop();f[x]=0;
for(int i=h[x];i;i=data[i].next){
int y=data[i].to;
if(d[x]+data[i].val<d[y]){
d[y]=d[x]+data[i].val;
if(!f[y]) f[y]=1,q.push(y);
}
}
}
}
int main(){
//  freopen("a.in","r",stdin);
n=read();m=read();tt=read();
while(m--){
int x=read(),y=read(),val=read();
data[++num].to=y;data[num].next=h[x];h[x]=num;data[num].val=val;
data[++num].to=x;data[num].next=h[y];h[y]=num;data[num].val=val;
}
spfa();
while(tt--){
int x=read(),y=read();
printf("%d\n",d[x]+d[y]);
}
return 0;
}

Dijkstra+STL版，复杂度O(nlogn)

#include <bits/stdc++.h>
using namespace std;
#define N 50010
#define M 100010
#define inf 0x3f3f3f3f
#define pa pair<int,int>
inline int read(){
int x=0,f=1;char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9') x=x*10+ch-'0',ch=getchar();
return x*f;
}
int n,m,tt,h
,num=0,d
;
bool vis
;
struct edge{
int to,next,val;
}data[M<<1];
void Dijkstra(){
memset(d,0x3f,sizeof(d));
std::priority_queue<pa,vector<pa>,greater<pa> >q;//按first小根堆
q.push(make_pair(0,1));d[1]=0;
while(!q.empty()){
int x=q.top().second;q.pop();
if(vis[x]) continue;vis[x]=1;
for(int i=h[x];i;i=data[i].next){
int y=data[i].to;
if(d[x]+data[i].val<d[y]){
d[y]=d[x]+data[i].val;
q.push(make_pair(d[y],y));
}
}
}
}
int main(){
//  freopen("a.in","r",stdin);
n=read();m=read();tt=read();
while(m--){
int x=read(),y=read(),val=read();
data[++num].to=y;data[num].next=h[x];h[x]=num;data[num].val=val;
data[++num].to=x;data[num].next=h[y];h[y]=num;data[num].val=val;
}
Dijkstra();
while(tt--){
int x=read(),y=read();
printf("%d\n",d[x]+d[y]);
}
return 0;
}