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146 lines
3.2 KiB
Markdown
146 lines
3.2 KiB
Markdown
---
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id: 69a890af247de743333bd4cc
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title: "Challenge 223: QR Decoder"
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challengeType: 28
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dashedName: challenge-223
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---
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# --description--
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Given a 6x6 matrix (array of strings), representing a QR code, return the string of binary data in the code.
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- The QR code may be given in any rotation of 90 degree increments.
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- A correctly oriented code has a 2x2 group of `1`'s (orientation markers) in the bottom-left, top-left, and top-right corners.
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- The three 2x2 orientation markers are not part of the binary data.
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- The binary data is read left-to-right, top-to-bottom (like a book) when the QR code is correctly oriented.
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- A code will always have exactly one valid orientation.
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For example, given:
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```js
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[
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"110011",
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"110011",
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"000000",
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"000000",
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"110000",
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"110001"
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]
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```
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or given the same code with a different orientation:
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```js
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[
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"110011",
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"110011",
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"000000",
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"000000",
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"000011",
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"100011"
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]
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```
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Return `"000000000000000000000001"`, all the binary data excluding the three 2x2 orientation markers.
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# --hints--
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`decodeQr(["110011", "110011", "000000", "000000", "110000", "110001"])` should return `"000000000000000000000001"`.
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```js
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assert.equal(decodeQr(["110011", "110011", "000000", "000000", "110000", "110001"]), "000000000000000000000001");
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```
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`decodeQr(["100011", "000011", "000000", "000000", "110011", "110011"])` should return `"000000000000000000000001"`.
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```js
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assert.equal(decodeQr(["100011", "000011", "000000", "000000", "110011", "110011"]), "000000000000000000000001");
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```
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`decodeQr(["110011", "111111", "010000", "110000", "110011", "110100"])` should return `"001101000011000000110100"`.
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```js
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assert.equal(decodeQr(["110011", "111111", "010000", "110000", "110011", "110100"]), "001101000011000000110100");
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```
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`decodeQr(["011011", "101011", "101000", "100010", "110011", "111011"])` should return `"010001000100010101010110"`.
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```js
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assert.equal(decodeQr(["011011", "101011", "101000", "100010", "110011", "111011"]), "010001000100010101010110");
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```
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`decodeQr(["111100", "110001", "100011", "001101", "110011", "110011"])` should return `"010000100100100101001110"`.
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```js
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assert.equal(decodeQr(["111100", "110001", "100011", "001101", "110011", "110011"]), "010000100100100101001110");
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```
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# --seed--
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## --seed-contents--
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```js
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function decodeQr(qrCode) {
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return qrCode;
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}
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```
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# --solutions--
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```js
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function isOriented(code) {
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const markerIndices = [
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[0, 0],
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[0, 1],
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[0, 4],
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[0, 5],
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[1, 0],
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[1, 1],
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[1, 4],
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[1, 5],
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[4, 0],
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[4, 1],
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[5, 0],
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[5, 1]
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];
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for(const [row, col] of markerIndices) {
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if (code[row][col] !== '1') return false;
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}
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return true;
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}
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function rotate(code) {
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const newCode = ['', '', '', '', '', ''];
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for (let i = 0; i < 6; i++) {
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for (let j = 5; j >= 0; j--) {
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newCode[i] += code[j][i];
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}
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}
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return newCode;
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}
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function getData(code) {
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let data = '';
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data += code[0].substring(2, 4)
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data += code[1].substring(2, 4)
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data += code[2]
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data += code[3]
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data += code[4].substring(2)
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data += code[5].substring(2)
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return data;
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}
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function decodeQr(qrCode) {
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let code = [...qrCode];
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while(!isOriented(code)) {
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code = rotate(code);
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}
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return getData(code);
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}
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```
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