分析
二维最短路板子题
嗯，dis[v][j] 可以由dis[u][j-1]或dis[u][i]转移过来
注意，如果用SPFA + SLF + swap，队列操作一定要判空！！！！
代码
1 /************************** 2 User:Mandy.H.Y 3 Language:c++ 4 Problem:move 5 Algorithm: 6 **************************/ 7 8 #include<bits/stdc++.h> 9 10 using namespace std; 11 12 const int maxn = 1e4 + 5; 13 const int maxm = 5e4 + 5; 14 const int maxk = 13; 15 16 int n,m,k,size,s,t; 17 int first[maxn]; 18 int dis[maxn][maxk]; 19 bool vis[maxn][15]; 20 21 struct Node{ 22 int u,num,dis; 23 Node(int _u = 0,int _dis = 0,int _num = 0):u(_u),dis(_dis),num(_num){} 24 bool operator < (const Node &a) const { 25 return dis > a.dis; 26 } 27 }; 28 29 struct Edge{ 30 int v,w,nt; 31 }edge[maxm << 1]; 32 33 template<class T>inline void read(T &x){ 34 x = 0;bool flag = 0;char ch = getchar(); 35 while(!isdigit(ch)) flag |= ch == '-',ch = getchar(); 36 while(isdigit(ch)) x = (x << 1) + (x << 3) + (ch ^ 48),ch = getchar(); 37 if(flag) x = -x; 38 } 39 40 template<class T>void putch(const T x){ 41 if(x > 9) putch(x / 10); 42 putchar(x % 10 | 48); 43 } 44 45 template<class T>void put(const T x){ 46 if(x < 0) putchar('-'),putch(-x); 47 else putch(x); 48 } 49 50 void file(){ 51 freopen("move.in","r",stdin); 52 freopen("move.out","w",stdout); 53 } 54 55 void eadd(int u,int v,int w){ 56 edge[ ++ size].v = v; 57 edge[size].w = w; 58 edge[size].nt = first[u]; 59 first[u] = size; 60 } 61 62 void readdata(){ 63 read(n);read(m);read(k); 64 read(s);read(t); 65 for(int i = 1;i <= m; ++ i){ 66 int u,v,w; 67 read(u);read(v);read(w); 68 eadd(u,v,w); 69 eadd(v,u,w); 70 } 71 } 72 73 void Dijkstra(){ 74 priority_queue<Node>q; 75 memset(dis,0x3f3f3f3f,sizeof(dis)); 76 dis[s][0] = 0; 77 q.push(Node(s,0,0)); 78 while(!q.empty()){ 79 Node x = q.top(); 80 q.pop(); 81 if(vis[x.u][x.num]) continue; 82 vis[x.u][x.num] = 1; 83 int u = x.u,num = x.num; 84 for(int i = first[u];i;i = edge[i].nt){ 85 int v = edge[i].v; 86 int w = edge[i].w; 87 if(dis[v][num] > dis[u][num] + w){ 88 dis[v][num] = dis[u][num] + w; 89 q.push(Node(v,dis[v][num],num)); 90 } 91 if(num + 1 <= k && dis[v][num + 1] > dis[u][num]){ 92 dis[v][num + 1] = dis[u][num]; 93 q.push(Node(v,dis[v][num + 1],num + 1)); 94 } 95 } 96 } 97 } 98 99 void work(){ 100 Dijkstra(); 101 int ans = 2e9; 102 for(int i = 0;i <= k; ++ i) ans = min(ans,dis[t][i]); 103 //从0开始 104 put(ans); 105 } 106 107 int main(){ 108 // file(); 109 readdata(); 110 work(); 111 return 0; 112 }