無權單源最短路:直接廣搜
void Unweighted ( vertex s)
{
queue <int> Q;
Q.push( S );
while( !Q.empty() )
{
V = Q.front();
Q.pop();
for( each W adjacent to V )
{
if( dist[W] == -1 )
{
dist[W] = dist[V] + 1;
path[W] = V;
Q.push( W );
}
}
}
}
dist[W] = S ---- W of MinDist;
dist[S] = 0;
path[W] = S ---> W of vertex
Dijkstra算法思路:有權單源最短路
void Dijkstra ( )
{
while( 1 )
{
V = smallest unknow distance vertex; //未收錄頂點中dist最小者
if( no V ) //V不存在
break;
collected[V] = true; //收錄
for( each W adjacent to V ) //V的每個鄰接點W
{
if( collected[W] == false ) //如果未收錄
{
if( dist[V] + E(V, W) < dist[W] )
{ //路徑變短,更新一下
dist[W] = dist[V] + E(V, W);
path[W] = V; //path記錄路徑
}
}
}
}
}
Floyd算法思路:多源最短路,不過因爲其代碼簡單,在時間要求寬鬆時求給定兩點的最短路也可以用Floyd算法
void Floyd ( )
{
for( i=0; i<n; i++ )
{
for( j=0; j<n; j++ )
{
D[i][j] = G[i][j];
path[i][j] = -1;
}
}
for( k=0; k<n; k++ )
{
for( i=0; i<n; i++ )
{
for( j=0; j<n; j++ )
{
if( D[i][k] + D[k][j] < D[i][j] )
{
D[i][j] = D[i][k] + D[k][j];
path[i][j] = k;
}
}
}
}
}