Question: What is the total number of positions that two queens can exist on a chess board where they cannot attack each other?
Approach: My logic in this is to create variables of two queens which provides the coordinates of where they exist on the chess board. From there, move one queen (white queen) through every open position on the board and in each new position loop through the validation on whether or not the other queen (black queen) can attack it by using first confirming if they're on the same column or row. Then for the diagonal attack starting with diagonally down and to the right, use attack coordinate variables (the vx and vy values) to move down and to the right each time it checks to see if as it diagonally moves, if the black queen ends up with the same coordinates as the white queen before it runs off the board. The variables vx and vy are purposely set to a -1 after each validation path to be "off the board" so it doesn't accidently trigger a validation based on the number it left off at when the loop is completed.
Where The Problem Is: The code works all the way up until the else if line for the //validates diagonal down/right attack section (line 39+). It doesn't seem to matter what I put in there as the true statement, the result freezes the application and forces me to use the break command to get out of it. If I comment out the diagonal attack section, the program (as is) will run and return a value of 49. I'm trying to get to the answer of 42. The difference of 7 being the diagonal down/right attack pattern when the black queen is in the top left (0,0) position.
Once Solved: I know arrays would be easier, but at this point, I know there is change that would unblock this and if someone could show me what I'm missing, then the other three diagonal attack patterns is a matter of copy/paste the diagonal attack section and then change the + and - signs of the variables to change the diagonal movement of the attacking queen. From there would add in the while loop of the black queens movement across the board and down every time the white queen has iterated through the board on the black queen's new coordinates.
Your help would be greatly appreciated. Thank you so much for your time!
<!DOCTYPE html>
<html>
<body>
<h2>Answer To Two Queens Question</h2>
<p id="demo"></p>
<script>
//total number of positions the two queens cannot attack each other
var n = 0;
//white queen
var x1 = 0;
var y1 = 0;
//black queen
var x2 = 0;
var y2 = 0;
//validation attack path
var vx = -1;
var vy = -1;
//moves white queen down one row after iterating through all available options
while (y1 <= 7) {
//moves white queen across an entire row
while (x1 <= 7) {
//skips validation of attack patterns if queens are on the same square on the board (invalid scenario)
if (x1==x2 && y1==y2){
x1 = x1 + 1;
//validates horizontal attack (left & right)
} else if (x1 == x2) {
x1 = x1 + 1;
//validates vertical attack (up & down)
} else if (y1 == y2){
x1 = x1 + 1;
//validates diagonal down/right attack
} else if (1 == 1) {
//sets validation coordinates to be the same as the black queen
vx = x2;
vy = y2;
//iterates through diagonal down/right attack coordinates to see if it matches same coordinates of white queen
while(vx <= 7 && vy <= 7){
if (x2 + vx == x1 && y2 + vy == y1) {
x1 = x1 + 1;
} else {
vx = vx + 1;
vy = vy + 1;
}
}
vx = -1;
vy = -1;
//if all validations fail, count towards total count where they cannot attack
} else {
n = n + 1;
x1 = x1 + 1;
}
}
y1 = y1 + 1;
x1 = 0;
}
document.getElementById("demo").innerHTML = "The number positions where two queens cannot attack each other is " + n;
</script>
</body>
</html>
question from:
https://stackoverflow.com/questions/65836721/javascript-stuck-on-diagonal-validation-of-two-queens-and-if-they-can-attack-ea 与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
