Prim algorithm for Hihocoder 1109 heap optimization

Topic Links: http://hihocoder.com/problemset/problem/1109, minimum spanning tree + heap optimization (priority queue).

Can use the priority queue, or you can manually simulate the heap, in order to practiced hand, I have tried both, priority queue or to be convenient, but the heap to be faster.

Learn the algorithm well, there is no gratuitous love, there is no reason to reduce the complexity of time.

　

Heap-Optimized code:

#include <iostream>#include<cstdio>#include<vector>#include<queue>#include<cmath>#include<string>#include<string.h>#include<algorithm>using namespacestd;#defineLL __int64#defineEPS 1e-8#defineINF 1e8#defineLson L, M, RT << 1#defineRson m + 1, R, RT << 1 | 1Const intMOD =2333333; Const intMAXN =100000+5;structEdge {//adjacency Table representation diagram    intV, W; BOOL operator< (ConstEdge &tmp)Const {        returnW <TMP.W; }} a[maxn];vector<Edge>E[MAXN];intVIS[MAXN], DIST[MAXN];voidPushup (intRtintR) {        //update from bottom up with RT as Root, R to right boundary heap    inti = r >>1;  while(I >=RT) {        if(A[r] <A[i])            {Swap (A[r], a[i]); R=i; I>>=1; } Else {             Break; }    }}voidPushdown (intRtintR) {        //update from top to bottom with RT as Root, R to right boundary heap    inti = RT <<1;  while(I <=r) {if(A[i].w > A[i +1].w) I++; if(A[i] <A[rt])            {Swap (A[i], a[rt]); RT=i; I<<=1; } Else {             Break; }    }}intPrim (intS,intN) {    intTot, ans;//tot represents the number of elements in the heaptot = ans =0; memset (Vis,0,sizeof(VIS));  for(inti =1; I <= N; i++) Dist[i]=INF; a[++TOT].V =s; A[TOT].W=0;  while(Tot >=1) {Edge u= a[1]; Swap (a[1], A[tot]); A[tot--].W =INF; Pushdown (1, tot); if(VIS[U.V])Continue; Ans+=U.W; VIS[U.V]=1;  for(inti =0; I < e[u.v].size (); i++) {            intj =e[u.v][i].v; if(Dist[j] >E[U.V][I].W) {Dist[j]=E[U.V][I].W; if(!Vis[j]) {a[++tot] =E[u.v][i]; Pushup (1, tot); }            }        }    }    returnans;}intMain () {intN, M, U, V, W; scanf ("%d%d", &n, &m);  while(m--) {scanf (" %d%d%d", &u, &v, &W); Edge tmp={V, w};        E[u].push_back (TMP); TMP.V=u;    E[v].push_back (TMP); } printf ("%d\n", Prim (1, N)); return 0;}

Priority Queue Optimization (note the details of overloaded operator places):

#include <iostream>#include<cstdio>#include<vector>#include<queue>#include<cmath>#include<string>#include<string.h>#include<algorithm>using namespacestd;#defineLL __int64#defineEPS 1e-8#defineINF 1e8#defineLson L, M, RT << 1#defineRson m + 1, R, RT << 1 | 1Const intMOD =2333333; Const intMAXN =100000+5;structEdge {intV, W; BOOL operator< (ConstEdge &tmp)Const {        returnW >TMP.W; }} a[maxn];vector<Edge>E[MAXN];intVIS[MAXN], DIST[MAXN];intPrim (Edge S,intN) {Priority_queue<Edge>que; intAns =0;  for(inti =1; I <= N; i++) {Dist[i]=INF; Vis[i]=0;    } que.push (s);  while(!Que.empty ()) {Edge U=Que.top ();        Que.pop (); if(VIS[U.V])Continue; VIS[U.V]=1; Ans+=U.W;  for(inti =0; I < e[u.v].size (); i++) {            intj =e[u.v][i].v; if(Dist[j] > E[U.V][I].W &&!Vis[j]) {Dist[j]=E[U.V][I].W;            Que.push (E[u.v][i]); }        }    }    returnans;}intMain () {intN, M, U, V, W; scanf ("%d%d", &n, &m);  while(m--) {scanf (" %d%d%d", &u, &v, &W); Edge tmp={V, w};        E[u].push_back (TMP); TMP.V=u;    E[v].push_back (TMP); } Edge tmp= {1,0}; printf ("%d\n", Prim (TMP, n)); return 0;}

Prim algorithm for Hihocoder 1109 heap optimization