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Update rotateMatrix.js #24

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160 changes: 52 additions & 108 deletions chapter01/1.7 - Rotate Matrix/rotateMatrix.js
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Original file line number Diff line number Diff line change
@@ -1,108 +1,52 @@
var rotateMatrix = function(matrix) {
var edge = matrix.length - 1;

var movePixels = function(row, col) {
// starts at m[row][col]
// moves to m[col][edge - row]
var fromRow;
var fromCol;
var fromPixel;

// first transformation
var toRow = row; // 0
var toCol = col; // 1
var toPixel = matrix[row][col];

// Do rotational transformation 4 times
for (var i = 0; i < 4; i++) {
fromRow = toRow;
fromCol = toCol;
toRow = fromCol;
toCol = edge - fromRow;

fromPixel = toPixel;
toPixel = matrix[toRow][toCol];
matrix[toRow][toCol] = fromPixel;
}
};

for (var i = 0; i < matrix.length / 2; i++) {
for (var j = i; j < edge - i; j++) {
console.log(i, j);
movePixels(i, j);
}
}
};


/* TEST */
var testMatrix = [
[1, 2, 3, 4],
[0, 1, 2, 3],
[0, 0, 1, 2],
[1, 0, 0, 1]
];

console.log('before:');
console.log(testMatrix[0]);
console.log(testMatrix[1]);
console.log(testMatrix[2]);
console.log(testMatrix[3]);

rotateMatrix(testMatrix);

console.log('after:');
console.log(testMatrix[0]);
console.log(testMatrix[1]);
console.log(testMatrix[2]);
console.log(testMatrix[3]);

/*
var edge = n - 1;

pattern observed:
i) col value becomes row value
ii) row value is subtracted off edge and becomes col value

0100
0000
0000
0000

position of 1 -> m[0][1]

0000
0001
0000
0000

position of 1 -> m[1][edge]

0000
0000
0000
0010

position of 1 -> m[edge][edge - 1]

0000
0000
1000
0000

position of 1 -> m[edge-1][0]

0100
0000
0000
0000

position of 1 -> m[0][1]

flow of iteration:
i) start from top left corner and move diagonally down
ii) for each row, iterate pixels until edge - 1
(pixel at edge would have been transformed by the first pixel)
iii) at each pixel iteration, iterate through 4 sides
iv) do iteration in place, i.e. store a temp pixel for moving things around
*/
function rotate(pic) {
let rotatePic = [];

for (let i=0; i<pic.length; i++) {
for (let j=0; j<pic.length; j++) {
if (!rotatePic[j]) {
rotatePic[j] = [];
}
rotatePic[j][(pic[i].length-1)-i] = pic[i][j];
}
}
printPic(pic);
printPic(rotatePic);

return rotatePic;
}

function printPic(pic) {
console.log('###')
for (let i=0; i<pic.length; i++) {
console.log(pic[i].join(''));
}
console.log('###')
}

function areEqual(arr1, arr2) {
if (arr1.length !== arr2.length) {
return false;
}

for (let i=0; i<arr1.length; i++) {
if (arr1[i].length !== arr2[i].length) {
return false;
}
for (let j=0; j<arr1.length; j++) {
if (arr1[i][j] !== arr2[i][j]) {
return false;
}
}
}

return true;
}

console.log(areEqual(
rotate([[1,1,1,1],[2,2,2,2],[3,3,3,3],[4,4,4,4]]),
[[4,3,2,1],[4,3,2,1],[4,3,2,1],[4,3,2,1]])
);
console.log(areEqual(
rotate([[8,0,1,0],[1,2,2,6],[9,7,3,3],[9,1,4,9]]),
[[9,9,1,8],[1,7,2,0],[4,3,2,1],[9,3,6,0]])
);