HDU 1233 or unblocked project (minimum spanning tree)

Think about it, this is one of the bare minimum spanning tree topics.

Here are two ways to calculate prim and kruscal

Of course, because the subject is a dense edge.

So actually the prim algorithm is a little bit better

Prim

1 /*2 minimum spanning tree, prim algorithm3 */4#include <cstdio>5#include <cstring>6#include <algorithm>7 8 using namespacestd;9 Const intN = the;Ten Const intINF =0x3f3f3f3f; One  A intK, Fa[n], minn[n], first[n], vis[n];//Vis[n] Indicates whether to add to the saved collection -  - structedge{ the     inty, Next, D; -     BOOL operator< (ConstEdge & M)Const{ -         returnD <M.D; -     } +}e[n*N]; -  + voidAdd_edge (intXintYintd) A { atE[k].y = y, E[k].next = first[x], E[K].D =D; -FIRST[X] = k++; - } -  - intPrimintSrcintN) - { inMEMSET (Minn,0x3f,sizeof(Minn)); -memset (Vis,0,sizeof(Vis)); toVIS[SRC] =1; +      for(inti = first[src]; i!=-1; I=e[i].next) -     { the         intv =e[i].y; *         if(!vis[v]) minn[v] =min (minn[v], e[i].d); $     }Panax Notoginseng     intAns =0; -      for(inti =1; I<n; i++) the     { +         intindex =0, Min =INF; A          for(intj =1; J<=n; J + +) the         { +             if(Minn[j] <Min) { -Min =Minn[j]; $index =J; $             } -         } -Ans + =Min; theMinn[index] =INF; -Vis[index] =1;//make index no longer accessibleWuyi         //Update the          for(intj = First[index]; j!=-1; j=e[j].next) -         { Wu             intv =e[j].y; -             if(!vis[v]) minn[v] =min (minn[v], e[j].d); About         } $     } -     returnans; - } -  A intMain () + { the    //freopen ("a.in", "R", stdin); -     intN, M, a, B, D; $      while(SCANF ("%d", &N), N) the     { them = N (n1) /2; the          for(inti =1; I<=n; i++) Fa[i] =i; the  -K =0; inmemset (First,-1,sizeof(first)); the          for(inti =0; I<m; i++){ thescanf"%d%d%d", &a, &b, &d); About Add_edge (A, B, d); the Add_edge (b, A, d); the         } the  +printf"%d\n", Prim (1, N)); -     } the     return 0;Bayi}

Kruscal:

1 /*2 minimum spanning tree, prim algorithm3 */4#include <cstdio>5#include <cstring>6#include <algorithm>7 8 using namespacestd;9 Const intN = the;Ten  One intK, fa[n]; A  - structedge{ -     intx, y, D; the     BOOL operator< (ConstEdge & M)Const{ -         returnD <M.D; -     } -}e[n*N]; +  - voidAdd_edge (intXintYintd) + { Ae[k].x = x, e[k].y = y, e[k].d =D; atk++; - } -  - intGet_head (intx) - { -      while(x! = fa[x]) x=Fa[x]; in     returnx; - } to  + BOOLUnion (intXinty) - { the     intfa_x =get_head (x); *     intFa_y =Get_head (y); $     if(Fa_x! =fa_y) {Panax NotoginsengFa[fa_x] =fa_y; -         return true; the     } +     return false; A } the  + intMain () - { $    //freopen ("a.in", "R", stdin); $     intN, M, a, B, D; -      while(SCANF ("%d", &N), N) -     { theK =0; -m = N (n1) /2;Wuyi  the          for(inti =1; I<=n; i++) Fa[i] =i; -  Wu          for(inti =0; I<m; i++){ -scanf"%d%d%d", &a, &b, &d); About Add_edge (A, B, d); $         } -Sort (E, e+k); -         intAns =0; -          for(inti =0; i<k; i++){ A             if(Union (e[i].x, e[i].y)) ans + =e[i].d; +         } theprintf"%d\n", ans); -     } $     return 0; the}

HDU 1233 or unblocked project (minimum spanning tree)