Problem Solving

birthday-cake-candles.js

// You are in charge of the cake for your niece's birthday 
// and have decided the cake will have one candle for each year of her total age. 
// When she blows out the candles, she’ll only be able to blow out the tallest ones. 
// Your task is to find out how many candles she can successfully blow out.


let ar = [3, 2, 1, 3, 2, 2, 2] // each element of array represents to size of candles

function birthdayCakeCandles(ar) {
    let max = 0;
    let max_freq = 0;
    
    for(let i = 0; i < ar.length; i++){
        if(ar[i] > max) {
            max = ar[i]
            max_freq = 1;
        }
      
        else if(ar[i] === max) {
            max_freq++
        }
       
    }
    return max_freq;

}

birthdayCakeCandles(ar);

find-second-highest.js

// find second highest value in array
// 8
// O(n)
//
"use strict"

let nums = [6,3,5,7,6,8,9,10,10,11,3,4,5,1,1,1]

function findSecondHighestValue(nums){
    let first = 0;
    let second = 0;
    for(let i = 0; i < nums.length; i++){
        if(nums[i] > first){
            second = first;
            first = nums[i]
        }
        if(nums[i] < first && nums[i] > second){
            second = nums[i]
        }

    }
    return second;
}

findSecondHighestValue(nums)

grades.js

// https://www.hackerrank.com/challenges/grading/problem
function gradingStudents(grades) { 
    return grades.map(n => {
        let diff = 5 - (n % 5)
        diff < 3 && n >= 38 
            ? n += diff
            : null
        return n 
    })

}

gradingStudents( [4, 73, 67, 38, 33 ] )

min-max-sum.js

// minimum four number and minumum five number ex: 1+2+3+4 and 2+3+4+5
//input: array output: number
function miniMaxSum(arr) {
    // sort numbers as an order  
    // take first four numbers
    // take last four numbers
        // slice arr.length - 4, arr.length
    // reduce first and last arrays
    let newArr = arr.sort()
    let firstFour = newArr.slice(0,4)
    let lastFour = newArr.slice(newArr.length -4, newArr.length)
    let maxResult = 0;
    let minResult = 0;
    
    maxResult = lastFour.reduce((c,r) => c + r) 
    minResult = firstFour.reduce((c,r) => c + r)
    console.log(minResult)
    console.log(maxResult)
}

miniMaxSum([4,1,3,5,2])

nMinus1-replaceType.js

function nMinus1(arr){
    let i = arr.length;
    while(i--) {
        if(i > 0) {
            if(arr[i].key === arr[i-1].key){
                arr[i-1].type += " " + arr[i].type 
                arr.splice(i,1)
            }
        }
        
    }
    
    return arr

}

nMinus1(
    [
        {
            "key": "str",
            "type": "int"

        },
        {
            "key": "str",
            "type": "bool"

        },
        {
            "key": "str",
            "type": "array"

        },
        {
            "key": "b",
            "type": "func"

        },
        {
            "key": "c",
            "type": "func"

        },
        {
            "key": "f",
            "type": "func"

        },
        {
            "key": "f",
            "type": "object"

        },
        {
            "key": "f",
            "type": "string"

        }
    ]
)

staircase.js

// Write a program that prints a staircase of size .
// Consider a staircase of size : n = 4

//    #
//   ##
//  ###
// ####

function staircase(n){
   let stairLayer = []
   for(let i = 0; i < n; i++){
       //  decreasing n number
       let stairBlock = []
       let skipBlock = n - i - 1; // -1 because i starts with 0
       
       for(let j = 0; j < n; j++){
           debugger
           if(skipBlock > 0) stairBlock.push(' ')
           else stairBlock.push('#')
           skipBlock--
       }
        
    stairLayer.push(stairBlock)
   }
   
   for(let s of stairLayer) {
    console.log(s.join(''))    
   }
}

staircase(3)

time-conversion.js

// input: 07:05:45PM
// expected output: 19:05:45

function timeConversion(s){
    s = s.split(':')  
    
    if(s[0] < 12 && s[2].includes('PM')) {
        s[0] = parseInt(s[0],0) + 12
    }
    if(s[0] == 12 && s[2].includes('AM')) {
        s[0] = '00'
    }
    s[2].includes('PM') 
        ? s[2] = s[2].replace('PM','')
        : null
    
    s[2].includes('AM') 
        ? s[2] = s[2].replace('AM','')
        : null
    
    s[0] = s[0].toString()

    console.log(`${s[0]}:${s[1]}:${s[2]}`)
}

timeConversion('03:05:45PM')
timeConversion('12:40:22AM')