最短路dijkstra(堆实现)

#include<iostream>#include<cstdio>#include<cstring>using namespace std;#include<queue>#define inf 0x3f3f3f3f#define mxn 2002struct point {int num,c;bool operator < ( const point & b ) const {return c < b.c;}bool operator > ( const point & b ) const {return c > b.c;}};int first[mxn], nxt[mxn], to[mxn], cost[mxn], dis[mxn], e;void add( int u, int v, int c ) {to[e] = v;cost[e] = c;nxt[e] = first[u];first[u] = e++;}void dijkstra( int s ) {memset( dis, 0x3f, sizeof( dis ) );priority_queue< point, vector<point>, greater< point > > q;point p;dis[s] = 0;p.num = s, p.c = 0;q.push( p );while( ! q.empty() ) {point p1 = q.top();q.pop();if( dis[p1.num] != p1.c ) continue;for( int i = first[p1.num]; i != -1; i = nxt[i] ) {int v = to[i];if( dis[v] > dis[p1.num] + cost[i] ) {dis[v] = dis[p1.num] + cost[i];point p2;p2.num = v;p2.c = dis[v];q.push( p2 );}}}}int main() {int n,m;while( scanf( "%d%d", &n, &m ) != EOF ) {e = 0;memset( first, -1, sizeof( first ) );for( int i = 1; i <= m; ++i ) {int u, v, c;scanf( "%d%d%d", &u, &v, &c );add( u, v, c );add( v, u, c );}int st,end;scanf( "%d%d", &st, &end );dijkstra( st );if( dis[end] == inf )printf( "-1\n" );elseprintf( "%d\n", dis[end] );}return 0;}