T MaxLoading(T w[], T c, int n)
{// Return value of best loading.
// Use FIFO branch and bound.
// initialize for level 1 start
LinkedQueue<T> Q; // live-node queue
Q.Add(-1); // end-of-level marker
int i = 1; // level of E-node
T Ew = 0, // weight of E-node
bestw = 0; // best weight so far
// search subset space tree
while (true) {
// check left child of E-node
if (Ew + w[i] <= c) // x[i] = 1
AddLiveNode(Q, Ew + w[i], bestw, i, n);
// right child is always feasible
AddLiveNode(Q, Ew, bestw, i, n); // x[i] = 0
Q.Delete(Ew); // get next E-node
if (Ew == -1) { // end of level
if (Q.IsEmpty()) return bestw;
Q.Add(-1); // end-of-level marker
Q.Delete(Ew); // get next E-node
i++;} // level number of Ew
}
}
void LevelOrder(BinaryTreeNode<T> *t)
{// Level-order traversal of *t.
LinkedQueue<BinaryTreeNode<T>*> Q;
while (t) {
Visit(t); // visit t
// put t's children on queue
if (t->LeftChild) Q.Add(t->LeftChild);
if (t->RightChild) Q.Add(t->RightChild);
// get next node to visit
try {Q.Delete(t);}
catch (OutOfBounds) {return;}
}
}
void AddLiveNode(LinkedQueue<T> &Q, T wt,
T& bestw, int i, int n)
{// Add node weight wt to queue Q if not leaf.
if (i == n) {// feasible leaf
if (wt > bestw) bestw = wt;}
else Q.Add(wt); // not a leaf
}
int mains() {
// Demonstrate that our LinkedQueue works.
LinkedQueue numbers;
numbers.Add(4);
numbers.Add(8);
numbers.Add(15);
numbers.Add(16);
numbers.Add(23);
numbers.Add(42);
while (numbers.Size() > 0) {
int data = numbers.Remove();
cout << "Removed " << data << endl;
}
// This seems to work! Yay!
// But there are sinister bugs hidden from view...
// First, what happened to the Nodes that got unlinked from the queue?
// Second, what happens if I Remove from an empty queue?
// Now that we've fixed those errors...
// Third, what's up with this code?
LinkedQueue second;
second.Add(1);
LinkedQueue copy = second; // make a copy of second
copy.Add(2);
cout << second.Size() << endl; // output: 1
cout << copy.Size() << endl; // output: 2
second.Remove();
copy.Remove();
// whoops! What happened?
// One final bug:
if (true) {
LinkedQueue third;
third.Add(5);
third.Add(6);
// What happens when third goes out of scope?
// What do we need to fix this?
}
for (int i = 0; i < 0; i++) {
LinkedQueue temp;
temp.Add(1);
temp.Add(1);
temp.Add(1);
temp.Add(1);
temp.Add(1);
}
LinkedQueue empty;
cout << empty.Remove();
return 0;
}
bool FindPath(Position start, Position finish,
int& PathLen, Position * &path)
{// Find a path from start to finish.
// Return true if successful, false if impossible.
// Throw NoMem exception if inadequate space.
if ((start.row == finish.row) &&
(start.col == finish.col))
{PathLen = 0; return true;} // start = finish
// initialize wall of blocks around grid
for (int i = 0; i <= m+1; i++) {
grid[0][i] = grid[m+1][i] = 1; // bottom & top
grid[i][0] = grid[i][m+1] = 1; // left & right
}
// initialize offsets
Position offset[4];
offset[0].row = 0; offset[0].col = 1; // right
offset[1].row = 1; offset[1].col = 0; // down
offset[2].row = 0; offset[2].col = -1; // left
offset[3].row = -1; offset[3].col = 0; // up
int NumOfNbrs = 4; // neighbors of a grid position
Position here, nbr;
here.row = start.row;
here.col = start.col;
grid[start.row][start.col] = 2; // block
// label reachable grid positions
LinkedQueue<Position> Q;
do {// label neighbors of here
for (int i = 0; i < NumOfNbrs; i++) {
nbr.row = here.row + offset[i].row;
nbr.col = here.col + offset[i].col;
if (grid[nbr.row][nbr.col] == 0) {
// unlabeled nbr, label it
grid[nbr.row][nbr.col]
= grid[here.row][here.col] + 1;
if ((nbr.row == finish.row) &&
(nbr.col == finish.col)) break; // done
Q.Add(nbr);} // end of if
} // end of for
// have we reached finish?
if ((nbr.row == finish.row) &&
(nbr.col == finish.col)) break; // done
// finish not reached, can we move to a nbr?
if (Q.IsEmpty()) return false; // no path
Q.Delete(here); // get next position
} while(true);
// construct path
PathLen = grid[finish.row][finish.col] - 2;
path = new Position [PathLen];
// trace backwards from finish
here = finish;
for (int j = PathLen-1; j >= 0; j--) {
path[j] = here;
// find predecessor position
for (int i = 0; i < NumOfNbrs; i++) {
nbr.row = here.row + offset[i].row;
nbr.col = here.col + offset[i].col;
if (grid[nbr.row][nbr.col] == j+2) break;
}
here = nbr; // move to predecessor
}
return true;
}
