https://www.cnblogs.com/chuninggao/p/7301083.html
SPFA算法(邻接表):
#include <iostream>
#include <cstdio>
#include <queue>
#include <cstring>
using namespace std;
const int maxn = 4010;
const int MAX = 0x3f3f3f3f;
int dis[maxn];
int n, m, head[maxn], d[maxn], time[maxn];
bool visit[maxn];
struct node
{
int u, v, w, next;
}mp[maxn];
bool sfpa(int s, int n)
{
for(int i=1; i<=n; i++)
{
dis[i]= MAX;
}
queue<int>q;
int x;
memset(visit, 0, sizeof(visit));
memset(time, 0, sizeof(time));
visit[s] = 1;
dis[s] = 0;
q.push(s);
while(!q.empty())
{
x = q.front();q.pop();
visit[x] = 0;
for(int i=head[x]; i!=-1; i = mp[i].next)
{
if(dis[mp[i].v]>dis[x]+mp[i].w)
{
dis[mp[i].v]=dis[x]+mp[i].w;
if(!visit[mp[i].v])
{
visit[mp[i].v] = 1;
q.push(mp[i].v);
if(++time[mp[i].v]>=n)
return 1;
}
}
}
}
printf("%d\n", dis[n]);
return 0;
}
int main()
{
int n, m, a, b, c, top;
scanf("%d%d", &m,&n);
top = 0;
memset(head, -1, sizeof(head));
for(int i=1; i<=m; i++)
{
scanf("%d%d%d", &a, &b, &c);
mp[top].u = a;
mp[top].v = b;
mp[top].w = c;
mp[top].next = head[a];
head[a] = top++;
mp[top].u = b;
mp[top].v = a;
mp[top].w = c;
mp[top].next = head[b];
head[b] = top++;
}
sfpa(1, n);
return 0;
}
Dijkstra算法(邻接表+队列优化):
struct point
{
int val,id;
point(int id,int val):id(id),val(val){}
bool operator <(const point &x)const{
return val>x.val;
}
};
void dijkstra(int s)
{
memset(vis,0,sizeof(vis));
for(int i=0;i<n;i++)
dis[i]=INF;
priority_queue<point> q;
q.push(point(s,0));
dis[s]=0;
while(!q.empty())
{
int cur=q.top().id;
q.pop();
if(vis[cur]) continue;
vis[cur]=true;
for(int i=head[cur];i!=-1;i=e[i].next)
{
int id=e[i].to;
if(!vis[id] && dis[cur]+e[i].val < dis[id])
{
dis[id]=dis[cur]+e[i].val;
q.push(point(id,dis[id]));
}
}
}
}