1 #include<iostream>
2 #include<string>
3 #include<queue>
4 #include<stack>
5 #include<vector>
6 #include<map>
7 #include<cstdio>
8 #include<cstdlib>
9 #include<algorithm>
10 #include<set>
11 #include<list>
12 #include<iomanip>
13 #include<cstring>
14 #include<cmath>
15 #include<limits>
16 using namespace std;
17
18 #define au auto
19 #define debug(i) cout<<"<debug> "<<i<<"<\debug>"<<endl
20 #define mfor(i,a,b) for(register int i=(a);i<=(b);i++)
21 #define mrep(i,a,b) for(register int i=(a);i>=(b);i--)
22 #define LLL __int128
23 #define Re register
24 #define il inline
25 #define mem(a,b) memset(a,(b),sizeof(a))
26 typedef pair<int, int> intpair;
27 typedef long long int LL;
28 const int INF = 0x3f3f3f3f;
29 const long long int INFLL = 0x3f3f3f3f3f3f3f3f;
30
31 int cnt;
32 const int maxn = 5000010;
33 int n, m, k;
34
35 struct Edge
36 {
37 int u, nxt;
38 int w;
39 }e[maxn];
40
41 int head[maxn];
42
43 void add(int a, int b, int w)
44 {
45 e[++cnt].u = b;
46 e[cnt].nxt = head[a];
47 head[a] = cnt;
48 e[cnt].w = w;
49 }
50
51 typedef struct
52 {
53 bool operator ()(const intpair& a, const intpair& b)const
54 {
55 return a.second > b.second;
56 }
57 }cmp;
58
59 int dis[maxn];
60 bool vis[maxn];
61 priority_queue<intpair, vector<intpair>, cmp>q;
62
63 void dijstra(int x)
64 {
65 mem(dis, 0x3f);
66 mem(vis, false);
67 dis[x] = 0;
68 q.push(intpair(x, dis[x]));
69 while (!q.empty())
70 {
71 intpair t = q.top();
72 q.pop();
73 if (vis[t.first]) continue;
74 vis[t.first] = true;
75 for (int i = head[t.first]; i != -1; i = e[i].nxt)
76 {
77 int u = e[i].u;
78 int w = e[i].w;
79 if (!vis[u] && dis[u] > t.second + w)
80 {
81 dis[u] = t.second + w;
82 q.push(intpair(u, dis[u]));
83 }
84 }
85 }
86 }
87
88 int main()
89 {
90 cin >> n >> m >> k;
91 mem(head, -1);
92 mfor(i, 1, m)
93 {
94 int a, b, c;
95 cin >> a >> b >> c;
96 add(a, b, c);
97 add(b, a, c);
98 mfor(j, 1, k)
99 {
100 add(j * n + a, j * n + b, c);
101 add(j * n + b, j * n + a, c);
102 add((j - 1) * n + a, j * n + b, 0);
103 add((j - 1) * n + b, j * n + a, 0);
104 }
105 }
106 dijstra(1);
107 int ans = dis[n];
108 mfor(i, 1, k)
109 {
110 ans = min(ans, dis[i * n + n]);
111 }
112 cout << ans;
113 return 0;
114 }
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