arraysLab.js

// # Arrays Lab
//
// To complete this lab (as for most labs), do the following:
//
// 1. Fork this repo.
// 2. Clone **your** forked repo.
// 3. Create a file called `arrays_lab.js` inside your cloned repo.
// 4. Copy the description of the exercise as a comment.
// 5. Underneath the commented description write your code.
// 6. Ensure your solutions work properly!
// 7. Open PR against this repo.
//
// ___
//
// ## Exercises
//
// 1. Log the last element of an array.
let array1 = [1, 2, 3, 4, 5];
console.log(array1[array1.length - 1]);


// 2. Change the first element of an array to the string "something else".
let array2 = [1, 2, 3, 4, 5];
array2[0] = "something else";
console.log(array2[0]);


// 3. Add "mango" to the end of a fruits array ["strawberry", "banana"].
let fruits = ["strawberry", "banana"];
fruits.push("mango");
console.log(fruits[fruits.length - 1]);


// 4. Add "blueberry" to the front of the same fruits array.
fruits.unshift("blueberry");
console.log(fruits[0]);


// 5. Remove the last element of the fruits array.
fruits.pop();


// 6. console.log the length of the fruits array.
console.log(fruits.length);


// 7. Remove the first element of the fruits array.
fruits.shift();
console.log(fruits[0]);

// 8. Join all the elements in the fruits array with a '$'.
fruits.join("$");
console.log(fruits.join("$"));

//
// 9. Given two arrays, write code that logs the larger array.  If the arrays are the same length, log "They are the same size"
//
// ```js
// let firstArr = [1,2,3]
// let secondArr = [1,5,2,4]
//
// // log [1,5,2,4]
// ```
let firstArr = [1, 2, 3];
let secondArr = [1, 5, 2, 4];
if(firstArr.length === secondArr.length) {
  console.log("The arrays are equal size");
} else if(firstArr.length > secondArr.length) {
  console.log("firstArr is bigger")
} else if(firstArr.length < secondArr.length) {
  console.log("secondArr is bigger");
} else {
  console.log("Error");
}


// 10. Given an array, log its middle element.  If the middle of the array is between two elements, log both of them.
//
// ```js
// let hasExactMiddleArr = [1,5,3]
//
// // log 5
//
// let hasNoExactMiddleArr = [1,4,6,9]
//
// // log 4,6
//
// ```
let arr10 = [1, 2, 3, 4, 5];
if(arr10.length % 2 === 0) {
  console.log( arr10[( (arr10.length) / 2) + - 1] + " " + arr10[ (arr10.length / 2) ] );
} else if(arr10.length % 2 === 1) {
  console.log( arr10[ Math.floor(arr10.length / 2) ] );
} else {
  console.log("Error");
}

// 11. Write code that logs every value in an array using a for loop
//
// ```js
// let logMeOutFor = ["I", "am", "a", "happy", "array"]
//
// /* I
//   am
//   a
//   happy
//   array
// */
// ```
let logMeOutFor = ["I", "am", "a", "happy", "array"];
for(let i = 0; i < logMeOutFor.length; i++) {
  console.log(logMeOutFor[i]);
}

// 12. Write code that logs every value in an array using a while loop
//
// ```js
// let logMeOutWhile = ["I", "am", "a", "happy", "array"]
//
// /* I
//   am
//   a
//   happy
//   array
// */
// ```
let x = 0;
while(x < logMeOutFor.length) {
  console.log(logMeOutFor[x]);
  x++;
}


// 13. Write code that logs every value in an array using a for/of loop
//
// ```js
// let logMeOutForOf = ["I", "am", "a", "happy", "array"]
//
// /* I
//   am
//   a
//   happy
//   array
// */
// ```
let y;
for (y of logMeOutFor) {
  console.log(y);
}


// 14. Given an array of numbers, write code that logs the sum of all the numbers
//
// ```js
// let firstArrToSum = [1, 2, 3, 4, 5, 6]
// //  21
//
// let secondArrToSum = [1, 2, 3, 4, 5, -6]
// //  9
// ```
let firstArrToSum = [1, 2, 3, 4, 5, 6];
let secondArrToSum = [1, 2, 3, 4, 5, -6];
let temp1 = 0;
let temp2 = 0;
for(let i = 0; i < firstArrToSum.length; i++) {
  temp1 += firstArrToSum[i];
}
console.log(temp1);
for(let i = 0; i < secondArrToSum.length; i++) {
  temp2 += secondArrToSum[i];
}
console.log(temp2);


// 15. Given an array of numbers, write code that logs all the odd numbers
//
// ```js
//
// let evenAndOddArr = [1,5,2,4,11,12,99,100]
//
// // 1, 5, 11, 99
// ```
let evenAndOddArr = [1, 5, 2, 4, 11, 12, 99, 100];
for(let i = 0; i < evenAndOddArr.length; i++) {
  if(evenAndOddArr[i] === 1) {
    console.log(evenAndOddArr[i])
  } else if(evenAndOddArr[i] % 2 === 1) {
    console.log(evenAndOddArr[i]);
  }
}


// 16. Given an array of numbers, write code that logs the sum of all the even numbers
//
// ```js
//
// let evenAndOddArrToSum = [1,5,2,3,11,4,6]
//
// // 12
// ```
let evenAndOddArrToSum = [1, 5, 2, 3, 11, 4, 6];
let temp16 = 0;
for(let i = 0; i < evenAndOddArrToSum.length; i++) {
  if(evenAndOddArrToSum[i] % 2 === 0) {
    temp16 += evenAndOddArrToSum[i];
  }
}
console.log(temp16);
console.log("--------------------------------------");

// 17. Write code such that noDupeList has all the same numbers as dupeFriendlyList, but has no more than one of each number.
//
// ```js
// let dupeFriendlyList = [4,2,6,2,2,6,4,9,2,1]
// let noDupeList = []
//
// // noDupleList = [4, 2, 6, 9, 1]
//
// ```
let dupeFriendlyList = [4, 2, 6, 2, 2, 6, 4, 9, 2, 1];
let noDupeList = [];
for(let i = 0; i < dupeFriendlyList.length; i++) {
  if(noDupeList.length === 0) {
    noDupeList.push(dupeFriendlyList[0]);
    //console.log(noDupeList[0]);

  } else if(noDupeList.indexOf(dupeFriendlyList[i]) === -1) { //checks for unique items in the array
    noDupeList.push(dupeFriendlyList[i]);
    //console.log(noDupeList[i]);
  }
}
for(let i = 0; i < noDupeList.length; i++) {
  console.log(noDupeList[i]);
}
console.log("--------------------------------------");


// 18. Make an array that contains all elements that appear exactly once in someRepeatsAgain
//
// ```js
// let someRepeatsAgain = [25,11,30,31,50,28,4,37,13,20,24,38,28,14,44,33,7,43,39,35,36,42,1,40,7,14,23,46,21,39,11,42,12,38,41,48,20,23,29,24,50,41,38,23,11,30,50,13,13,16,10,8,3,43,10,20,28,39,24,36,21,13,40,25,37,39,31,4,46,20,38,2,7,11,11,41,45,9,49,31,38,23,41,16,49,29,14,6,6,11,5,39,13,17,43,1,1,15,25]
//
// // [ 44,33,35,42,12,48,30,50,8,3,10,28,24,36,21,1000,40,37,4,46,20,2,7,45,9,31,38,23,41,16,49,29,14,6,11,5,39,13,17,43,1,15,25 ]
//
//
// ```
let someRepeatsAgain = [25,11,30,31,50,28,4,37,13,20,24,38,28,14,44,33,7,43,39,35,36,42,1,40,7,14,23,46,21,39,11,42,12,38,41,48,20,23,29,24,50,41,38,23,11,30,50,13,13,16,10,8,3,43,10,20,28,39,24,36,21,13,40,25,37,39,31,4,46,20,38,2,7,11,11,41,45,9,49,31,38,23,41,16,49,29,14,6,6,11,5,39,13,17,43,1,1,15,25];

let finalArray18 = [ ];

for(let i = 0; i < someRepeatsAgain.length; i++) {
  if(finalArray18.length === 0) {
    finalArray18.push(someRepeatsAgain[0]);
  } else if(finalArray18.indexOf(someRepeatsAgain[i]) === -1) {
    finalArray18.push(someRepeatsAgain[i]);
  }
}
for(let i = 0; i < finalArray18.length; i++) {
  console.log(finalArray18[i]);
}
console.log("--------------------------------------");


// 19. Given an array of strings, find the the string with the most "a"s in it.
//
// ```js
// let mostAStrings = ["apes", "abba", "apple"]
//
// //"abba"
// ```
let mostAStrings = ["apes", "abba", "apple"]
function char_count(str, letter) {
  let letter_Count = 0;
  for(let position = 0; position < str.length; position++) {
    if(str.charAt(position) === letter) {
      letter_Count += 1;
    }
  }
  return letter_Count;
}
for(let i = 0; i < mostAStrings.length; i++) {
  char_count(mostAStrings[i], "a");
  console.log(char_count(mostAStrings[i], "a"));
}








// 20. Find the second smallest number in an Array of Ints
//
// ```js
// let secondSmallestArr = [11, 52, 10, 7, 50, 46, 79, 78, 13, 26, 83, 92, 89, 81, 1, 41, 4, 23, 57, 41, 80, 83, 41, 69]
//
// // 4
// ```