✨🔗 Add episode 29 links

Author: w3cj

episode_029/README.md

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+# Episode 29
+
+## 7 kyu
+
+* https://www.codewars.com/kata/playing-with-sets-sup-slash-sub/train/javascript
+
+## 6 kyu
+
+* https://www.codewars.com/kata/the-supermarket-queue/train/javascript
+* https://www.codewars.com/kata/count-characters-in-your-string/train/javascript
+* https://www.codewars.com/kata/weird-string-case/train/javascript

episode_029/count-characters-in-your-string.js

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+function count (string) {  
+  // an object to store the counts
+  const counts = {};
+  // iterate over the letters in the string
+  for (let i = 0; i < string.length; i++) {
+    const letter = string[i];
+    // if the current letter is not a property in the object
+      // set it 0
+    counts[letter] = counts[letter] || 0;
+    // increment the current letter in the object by 1
+    counts[letter]++;
+  }
+  return counts;
+}
+
+function count (string) {
+  return Array.prototype.reduce.call(string, (counts, letter) => {
+    counts[letter] = counts[letter] || 0;
+    counts[letter]++;
+    return counts;
+  }, {});
+}
+
+function count (string) {
+  return string.split('').reduce((counts, letter) => {
+    counts[letter] = counts[letter] || 0;
+    counts[letter]++;
+    return counts;
+  }, {});
+}
+
+function count (string) {
+  return [].reduce.call(string, (counts, letter) => {
+    counts[letter] = counts[letter] || 0;
+    counts[letter]++;
+    return counts;
+  }, {});
+}
+
+console.log(count('aba'), { a: 2, b: 1 }); 
+console.log(count(''), {});

episode_029/playing-with-sets-sup-slash-sub.js

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+// return true if s1 is a subset of s2
+function isSubsetOf(s1, s2){
+  // iterate over s1
+  for (let item of s1) {
+    // check if current value is in s2
+    // if not
+    if (!s2.has(item)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+function isSubsetOf(s1, s2) {
+  return [...s1].every(item => s2.has(item));
+}
+
+function isSubsetOf(s1, s2) {
+  return Array.from(s1).every(item => s2.has(item));
+}
+
+// function isSubsetOf(s1, s2) {
+//   return Array.prototype.every.call(s1, item => s2.has(item));
+// }
+
+function isSupersetOf(s1, s2){
+  return isSubsetOf(s2, s1);
+}
+
+
+let A1 = new Set([1,2,3]), A2 = new Set([3,2,1]), B = new Set([1,2,3,4,5]), X = new Set([1,2,4,5,6,7]);
+
+// console.log( isSubsetOf(A1,A1), 'A is contained in A' );
+// console.log( isSubsetOf(A1,A2), '{1,2,3} is contained in {3,2,1}' );
+// console.log( isSubsetOf(A1,B),  '{1,2,3} is contained in {1,2,3,4,5}' );
+// console.log( isSubsetOf(A1,X), '{1,2,3} is not contained in {1,2,4,5,6,7}' );
+
+console.log( isSupersetOf(A1,A1), 'A includes A' );
+console.log( isSupersetOf(A1,A2), '{1,2,3} includes {3,2,1}' );
+console.log( isSupersetOf(B,A1),  '{1,2,3} includes {1,2,3,4,5}' );
+console.log( isSupersetOf(A1,X), '{1,2,3} doesnt include {1,2,4,5,6,7}' );

episode_029/the-supermarket-queue.js

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+function queueTime(customers, n) {
+  // a place to store the total amount of time, initialized to 0
+  let totalTime = 0;
+  // a place to store the current wait time for each cashier
+  let tills = Array(n).fill(0);
+  
+  while (customers.length || tills.some(till => till > 0)) {
+    // find an open cashier
+    let tillIndex = tills.indexOf(0);
+    while (tillIndex !== -1) {
+      // if open cashier - remove first customer from queue and set at cashier
+      // advance queue to open cashiers (open cashier is 0)
+      const currentCustomer = customers.shift();
+      tills[tillIndex] = currentCustomer;
+      tillIndex = tills.indexOf(0);
+    }
+    
+    // move total time forward by 1
+    totalTime += 1;
+    // decrease the time remaining at all cashiers by 1
+    tills.forEach((till, index) => {
+      if (till > 0) {
+        tills[index] -= 1;
+      }
+    });
+  }
+
+  // return total amount of time
+  return totalTime;
+}
+
+console.log(queueTime([], 1), 0);
+console.log(queueTime([1,2,3,4], 1), 10);
+console.log(queueTime([2,2,3,3,4,4], 2), 9);
+console.log(queueTime([1,2,3,4,5], 100), 5);

episode_029/weird-string-case.js

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+function toWeirdCase(string, isUpperCase = true){
+  return string.split('').reduce((weirdCase, letter) => {
+    if (letter !== ' ') {
+      if (isUpperCase) {
+        weirdCase += letter.toUpperCase();
+      } else {
+        weirdCase += letter.toLowerCase();
+      }
+      isUpperCase = !isUpperCase;
+    } else {
+      weirdCase += ' ';
+      isUpperCase = true;
+    }
+    
+    return weirdCase;
+  }, '');
+}
+
+function toWeirdCase(string, isUpperCase = true){
+  return string.split('').reduce((weirdCase, letter) => {
+    if (letter !== ' ') {
+      if (isUpperCase) {
+        isUpperCase = !isUpperCase;
+        return weirdCase + letter.toUpperCase();
+      } else {
+        isUpperCase = !isUpperCase;
+        return weirdCase + letter.toLowerCase();
+      }
+    } else {
+      isUpperCase = true;
+      return weirdCase + ' ';
+    }
+  }, '');
+}
+
+function toWeirdCase(string, isUpperCase = true){
+  return string.split('').reduce((weirdCase, letter) => {
+    if (letter !== ' ') {
+      if (isUpperCase) {
+        isUpperCase = !isUpperCase;
+        return weirdCase + letter.toUpperCase();
+      } else {
+        isUpperCase = !isUpperCase;
+        return weirdCase + letter.toLowerCase();
+      }
+    } else {
+      isUpperCase = true;
+      return weirdCase + ' ';
+    }
+  }, '');
+}
+
+console.log(toWeirdCase('This'), 'ThIs');
+console.log(toWeirdCase('is'), 'Is');
+console.log(toWeirdCase('This is a test'), 'ThIs Is A TeSt');