feat(curriculum): add tests and solution (#42111)

* feat: add tests

* feat: add solution

curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-79-passcode-derivation.md

@@ -8,28 +8,54 @@ dashedName: problem-79-passcode-derivation
 
 # --description--
 
-A common security method used for online banking is to ask the user for three random characters from a passcode. For example, if the passcode was 531278, they may ask for the 2nd, 3rd, and 5th characters; the expected reply would be: 317.
+A common security method used for online banking is to ask the user for three random characters from a passcode. For example, if the passcode was `531278`, they may ask for the 2nd, 3rd, and 5th characters; the expected reply would be: `317`.
 
-The array, `keylog`, contains fifty successful login attempts.
+The arrays, `keylog1`, `keylog2`, and `keylog3`, contains fifty successful login attempts.
 
 Given that the three characters are always asked for in order, analyze the array so as to determine the shortest possible secret passcode of unknown length.
 
 # --hints--
 
-`passcodeDerivation(keylog)` should return a number.
+`passcodeDerivation(keylog1)` should return a number.
 
 ```js
-assert(typeof passcodeDerivation(keylog) === 'number');
+assert(typeof passcodeDerivation(_keylog1) === 'number');
 ```
 
-`passcodeDerivation(keylog)` should return 73162890.
+`passcodeDerivation(keylog1)` should return `531278`.
 
 ```js
-assert.strictEqual(passcodeDerivation(keylog), 73162890);
+assert.strictEqual(passcodeDerivation(_keylog1), 531278);
+```
+
+`passcodeDerivation(keylog2)` should return `1230567`.
+
+```js
+assert.strictEqual(passcodeDerivation(_keylog2), 1230567);
+```
+
+`passcodeDerivation(keylog3)` should return `73162890`.
+
+```js
+assert.strictEqual(passcodeDerivation(_keylog3), 73162890);
 ```
 
 # --seed--
 
+## --after-user-code--
+
+```js
+const _keylog1 = [
+  127,327,178,528,537,538,532,328,127,178,537,127,317,328,512,278,328,327,178,327,578,317,527,178,128,328,517,312,531,128,128,317,527,312,328,532,512,518,317,127,537,528,537,527,327,278,532,128, 318,517
+];
+const _keylog2 = [
+  305,367,256,123,357,120,125,307,236,256,356,267,357,256,356,136,257,107,126,567,567,105,120,237,367,120,367,135,207,167,367,367,307,125,120,130,367,230,106,356,126,106,130,123,307,127,306,167,136,126
+];
+const _keylog3 = [
+  319,680,180,690,129,620,762,689,762,318,368,710,720,710,629,168,160,689,716,731,736,729,316,729,729,710,769,290,719,680,318,389,162,289,162,718,729,319,790,680,890,362,319,760,316,729,380,319,728,716,
+];
+```
+
 ## --seed-contents--
 
 ```js
@@ -40,15 +66,50 @@ function passcodeDerivation(arr) {
 
 // Only change code above this line
 
-const keylog = [
+const keylog1 = [
   319,680,180,690,129,620,762,689,762,318,368,710,720,710,629,168,160,689,716,731,736,729,316,729,729,710,769,290,719,680,318,389,162,289,162,718,729,319,790,680,890,362,319,760,316,729,380,319,728,716,
 ];
 
-passcodeDerivation(keylog);
+passcodeDerivation(keylog1);
 ```
 
 # --solutions--
 
 ```js
-// solution required
+function passcodeDerivation(arr) {
+  const numbersInPasscode = [];
+  const relativePositions = new Array(10)
+    .fill()
+    .map(() => new Array(10).fill(0));
+
+  for (let i = 0; i < arr.length; i++) {
+    const curAttempt = arr[i]
+      .toString()
+      .split('')
+      .map(key => parseInt(key, 10));
+    for (let j = 0; j < curAttempt.length; j++) {
+      if (numbersInPasscode.indexOf(curAttempt[j]) === -1) {
+        numbersInPasscode.push(curAttempt[j]);
+      }
+      for (let k = j + 1; k < curAttempt.length; k++) {
+        relativePositions[curAttempt[j]][curAttempt[k]] += 1;
+      }
+    }
+  }
+
+  const ranks = {};
+  for (let i = 0; i < numbersInPasscode.length; i++) {
+    const curNumber = numbersInPasscode[i];
+    ranks[curNumber] = relativePositions[curNumber].filter(
+      count => count > 0
+    ).length;
+  }
+
+  const passcode = numbersInPasscode
+    .sort((i, j) => ranks[i] - ranks[j])
+    .reverse()
+    .join('');
+
+  return parseInt(passcode, 10);
+}
 ```