All language subtitles for 3. Breadth First Search Example

Now that we have implemented our first pathfinding algorithm breadth first search, let's put it to the
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test and execute it
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with a grid. And you can find this example in the attached project for this course, but I'm going to
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quickly show you how to use it.
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So you have the left click to put the start position, left click again to put the end position, and with
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the right click we can specify some walls between our two positions.
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This will actually make the map harder for the algorithm.
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And if we click execute, then we can get a step by step path from the origin to the final position.
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Now, let's see if we put the start position and the end position and execute the algorithm step by
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step.
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So the first step is actually to check the direction above.
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So we'll see.
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The next position is labeled two because we need two steps to go here.
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And in our queue we have [1, 2], which is this one.
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It's line one and two.
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Please note that the first line is zero and the first column is also zero.
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If we click next step again, then the right position was checked.
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But it's a wall, so nothing to do here.
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The next one would be down.
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So another wall, nothing to do here but the left position in this case, it's okay.
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So this would be added to the queue as well as the step number would be updated
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with two. Now,
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if we proceed, the first one to get out of the queue would be [1, 2], which is this one and we'll
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check top, left, down, which is already parsed so we don't count that and left.
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Let's do it.
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As you see this position ended because there's no way to continue.
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So the algorithm will just continue with this and this.
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And boom, now we have the end position.
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So this is how breadth first search works.
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Of course, it is good to keep in mind that this is the first step because we need to recreate the path
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and to recreate the path.
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We use the recursive function that we discussed in the previous section.