题目链接:
http://acm.hdu.edu.cn/showproblem.php?pid=1874
题意:
题解:
卿学姐视频： http://www.bilibili.com/video/av4224493/
代码:
spfa：
1 #include <bits/stdc++.h> 2 using namespace std; 3 typedef long long ll; 4 #define MS(a) memset(a,0,sizeof(a)) 5 #define MP make_pair 6 #define PB push_back 7 const int INF = 0x3f3f3f3f; 8 const ll INFLL = 0x3f3f3f3f3f3f3f3fLL; 9 inline ll read(){ 10 ll x=0,f=1;char ch=getchar(); 11 while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();} 12 while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();} 13 return x*f; 14 } 15 ////////////////////////////////////////////////////////////////////////// 16 const int maxn = 205+10; 17 18 std::vector<pair<int,int> > E[maxn]; 19 20 int n,m; 21 int d[maxn],inq[maxn]; 22 23 void init(){ 24 for(int i=0; i<maxn; i++) E[i].clear(); 25 for(int i=0; i<maxn; i++) inq[i] = 0; 26 for(int i=0; i<maxn; i++) d[i] = 1e9; 27 } 28 29 int main(){ 30 while(cin >> n >> m){ 31 init(); 32 for(int i=0; i<m; i++){ 33 int u,v,w; scanf("%d%d%d",&u,&v,&w); 34 E[u].push_back(MP(v,w)); 35 E[v].push_back(MP(u,w)); 36 } 37 38 int s,t; 39 scanf("%d%d",&s,&t); 40 41 queue<int> Q; 42 Q.push(s), d[s]=0, inq[s]=0; 43 while(!Q.empty()){ 44 int now = Q.front(); 45 Q.pop(); inq[now] = 0; 46 for(int i=0; i<(int)E[now].size(); i++){ 47 int v = E[now][i].first, w = E[now][i].second; 48 if(d[now]+w < d[v]){ 49 d[v] = d[now]+w; 50 if(inq[v]==1) continue; 51 inq[v] = 1; 52 Q.push(v); 53 } 54 } 55 } 56 57 if(d[t] == 1e9) printf("-1 "); 58 else printf("%d ",d[t]); 59 } 60 61 return 0; 62 }
dij：
1 #include <bits/stdc++.h> 2 using namespace std; 3 typedef long long ll; 4 #define MS(a) memset(a,0,sizeof(a)) 5 #define MP make_pair 6 #define PB push_back 7 const int INF = 0x3f3f3f3f; 8 const ll INFLL = 0x3f3f3f3f3f3f3f3fLL; 9 inline ll read(){ 10 ll x=0,f=1;char ch=getchar(); 11 while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();} 12 while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();} 13 return x*f; 14 } 15 ////////////////////////////////////////////////////////////////////////// 16 const int maxn = 205+10; 17 18 std::vector<pair<int,int> > E[maxn]; 19 20 int n,m; 21 int d[maxn]; 22 23 void init(){ 24 for(int i=0; i<maxn; i++) E[i].clear(); 25 for(int i=0; i<maxn; i++) d[i] = 1e9; 26 } 27 28 int main(){ 29 while(cin >> n >> m){ 30 init(); 31 for(int i=0; i<m; i++){ 32 int u,v,w; scanf("%d%d%d",&u,&v,&w); 33 E[u].push_back(MP(v,w)); 34 E[v].push_back(MP(u,w)); 35 } 36 37 int s,t; 38 scanf("%d%d",&s,&t); 39 40 priority_queue<pair<int,int> > Q; 41 d[s]=0; 42 Q.push(MP(-d[s],s)); 43 while(!Q.empty()){ 44 int now = Q.top().second; 45 Q.pop(); 46 for(int i=0; i<(int)E[now].size(); i++){ 47 int v = E[now][i].first, w = E[now][i].second; 48 if(d[now]+w < d[v]){ 49 d[v] = d[now]+w; 50 Q.push(MP(-d[v],v)); 51 } 52 } 53 } 54 55 if(d[t] == 1e9) printf("-1 "); 56 else printf("%d ",d[t]); 57 } 58 59 return 0; 60 }