HDU 1874 unblocked works continued (Shortest path)

Test instructions: Shortest path

Idea: Shortest Path template

1. Single Source Shortest path (Dijkstra)

#include <iostream>#include<stdio.h>using namespacestd;#defineMAXN 1010#defineTypec int#defineINF 0x3f3f3f3f//prevent back overflow, this can't be too bigBOOLVIS[MAXN];intPRE[MAXN];intCOST[MAXN][MAXN],LOWCOST[MAXN];voidDijkstra (Typec cost[][maxn],typec lowcost[],intNintBeg) {//Beg as the source point    inti,j,k,min;  for(i=0; i<n;++i) {Lowcost[i]=inf;vis[i]=false;p re[i]=-1; } Lowcost[beg]=0;  for(j=0; j<n;++j) {k=-1; Min=INF;  for(i=0; i<n;++i)if(!vis[i]&&lowcost[i]<Min) {Min=Lowcost[i]; K=i; }        if(k==-1) Break; VIS[K]=true;  for(i=0; i<n;++i)if(!vis[i]&&lowcost[k]+cost[k][i]<Lowcost[i]) {Lowcost[i]=lowcost[k]+Cost[k][i]; Pre[i]=K; }    }}intMain () {intN,m;//points, number of sides    inta,b,w,i,j; intS,t;//starting point, end Point     while(~SCANF ("%d%d",&n,&m)) {         for(i=0; i<n;++i) for(j=0; j<n;++j) Cost[i][j]=INF;  for(i=0; i<m;++i) {scanf ("%d%d%d",&a,&b,&W); if(W<cost[a][b]) cost[a][b]=cost[b][a]=w;//} scanf ("%d%d",&s,&t);        Dijkstra (cost,lowcost,n,s); if(Lowcost[t]!=inf) printf ("%d\n", lowcost[t]); Elseprintf"-1\n"); }    return 0;}

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2. Multi-source Shortest path (Floyd)

#include <iostream>#include<stdio.h>using namespacestd;#defineMAXN 1010#defineTypec int#defineINF 0x3f3f3f3f//prevent back overflow, this can't be too bigintPATH[MAXN][MAXN];intCOST[MAXN][MAXN],LOWCOST[MAXN][MAXN];voidFloyd (Typec Cost[][maxn],typec LOWCOST[][MAXN],intN) {    inti,j,k;  for(i=0; i<n;++i) for(j=0; j<n;++j) {Lowcost[i][j]=Cost[i][j]; if(I!=j&&cost[i][j]<inf) path[i][j]=i; Elsepath[i][j]=-1; }     for(k=0; k<n;++k) for(i=0; i<n;++i) for(j=0; j<n;++j)if(lowcost[i][k]+lowcost[k][j]<Lowcost[i][j]) {Lowcost[i][j]=lowcost[i][k]+Lowcost[k][j]; PATH[I][J]=Path[k][j]; }}intMain () {intN,m;//points, number of sides    inta,b,w,i,j; intS,t;//starting point, end Point     while(~SCANF ("%d%d",&n,&m)) {         for(i=0; i<n;++i) for(j=0; j<n;++j) Cost[i][j]=INF;  for(i=0; i<m;++i) {scanf ("%d%d%d",&a,&b,&W); if(W<cost[a][b]) cost[a][b]=cost[b][a]=w;//} scanf ("%d%d",&s,&t);        Floyd (Cost,lowcost,n); if(s==t) printf ("0\n"); Else if(Lowcost[s][t]!=inf) printf ("%d\n", lowcost[s][t]); Elseprintf"-1\n"); }    return 0;}

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HDU 1874 unblocked works continued (Shortest path)