Blue Bridge cup algorithm training shortest path [Bellman]

Transmission Door

Algorithm training Shortest time limit: 1.0s memory limit: 256.0MB 1 brocade sac 2 Jin sac 3 problem description

Given an n vertex, the forward graph of the M-Edge (some of which may be negative, but no negative ring is guaranteed). Please calculate the shortest path from point 1th to other points (vertices are numbered from 1 to n).

Input format

First line two integers n, M.

The next M-line, each line has three integers u, V, L, indicating that u to V has an edge of length L.

The output format is a total of n-1 lines, and line I represents the shortest path from point 1th to I+1. Sample Input 3 3 1 2-1 2 3-1 3 1 2 Sample output-1-2 data size and conventions

For 10% of data, n = 2,m = 2.

For 30% of data, n <= 5,m <= 10.

For 100% of data, 1 <= n <= 20000,1 <= m <= 200000,-10000 <= L <= 10000, guaranteeing that all vertices can be reached from any vertex.

Exercises

Because of the ring, there is negative power, so with Bellman-ford

Because the data is a bit large, it is optimized with the queue

506328

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Shortest circuit

04-07 17:24

1.055KB

C++

That's right

100

171ms

4.003MB

Evaluation details

1#include <cstdio>2#include <algorithm>3#include <cstring>4#include <queue>5#include <vector>6 7 using namespacestd;8 9 Const intN =20005;Ten Const intINF =0x3f3f3f3f; One  Atypedefstruct - { -     intto ; the     intdis; - }pp; -  - intn,m; +Vector<pp>Bian[n]; - intV[n]; + intVis[n]; A  at voidBellman () - { -queue<int>que; -     intte,nt; -Que.push (1); -vis[1]=1; in     inti; -     intdis; to      while(Que.size () >=1) +     { -Te=Que.front (); the Que.pop (); *          for(i=0; I<bian[te].size (); i++){ $Nt=bian[te][i].to;Panax Notoginsengdis=Bian[te][i].dis; -             if(v[nt]>v[te]+dis) { thev[nt]=v[te]+dis; +                 if(vis[nt]==0){ Avis[nt]=1; the Que.push (NT); +                 } -             } $         } $vis[te]=0; -     } - } the  - intMain ()Wuyi { the     inti,j; -     intuu,vv,l; Wu PP te; -     //freopen ("data.in", "R", stdin); About     //while (scanf ("%d%d", &n,&m)!=eof) $scanf"%d%d",&n,&m); -     { -memset (Vis,0,sizeof(Vis)); -Fill (v,v+n+1, INF); Av[1]=0; +          for(i=0; i<=n;i++){ the bian[i].clear (); -             //printf ("i=%d v=%d\n", I,v[i]); $         } the          for(i=1; i<=m;i++){ thescanf"%d%d%d",&uu,&vv,&l); thete.to=vv;te.dis=l; the bian[uu].push_back (TE); -         } in Bellman (); the          for(i=2; i<=n;i++){ theprintf"%d\n", V[i]); About         } the     } the     return 0; the}

Blue Bridge cup algorithm training shortest path [Bellman]