}

​

//Multiples of 3 or 5

function p1(n){

  let sum = 0;

  for(let i = 1; i < n; i++){

    if(i % 3 == 0 || i % 5 == 0){

      sum += i;

    }

  }

  return sum;

}

​

​

​

//Even Fibonacci numbers

function p2(limit){

  let n1 = 1;

  let n2 = 2;

  let temp = 0;

  while (n2 < limit){

    temp = n2;

    n2 = n1 + n2;

    if(temp % 2 == 0){result += temp;}

  }

  return result;

}

​

​

​

​

//smallest multiple

function p5(n){

  let result = 1;

  while(true){

    let check = 0;

    for(let i = 0; i <= n; i++){

      if(result % i == 0){

        check++;

      }

    }

    if(check == n){

      break

    }else{

      result ++;

    }

  }

  console.log(result);

}

//Sum square difference

function p6(n){

  let squaredSum = 0;

  let sum = 0;

  for(let i = 1; i <= n; i++){

    squaredSum += i*i;

    sum += i;

  }

  console.log(sum*sum - squaredSum);

}

​

//Longest Collatz Sequence

function p14(){

  let record = 0;

  let largestSeqGen = 1;

  for(let i = 1; i <= 1000000; i++){

    let seqLen = 0;

    let t = i;

    while(t != 1){

      if(t % 2 == 0){

        t = t/2;

      }else{

        t = 3 * t + 1

      }

      seqLen++;

    }

    if(seqLen > record){

      record = seqLen;

      largestSeqGen = i;

    }

  }

  console.log(`The longest sequnece is ${record} generated by ${largestSeqGen}`);

}

//Lychel Numbers

function p55(){

  let lychrelCount = 0;

  let number;

  for(let i = 1; i <= 10000; i++){

    number = i;

    let count = 0;

    for(let j = 1; j <= 50; j++){

      //get flipped number

      const numberReversed = flip(number);

      const result = number + numberReversed;

      //check if palindrome

      if(result != flip(result)){

        number = result;

        count++;

      }else{

        break

      }

    }

    //see if count reached 50 i.e. a lychrel number

    if(count == 50){

      lychrelCount++;

    }

  }

  console.log(lychrelCount);

}

function flip(x){

  let tempArray = [];

  for(let i = str(x).length; i >= 0; i--) {tempArray.push(str(x)[i]);}

  return int(tempArray.join(''));

}

//Path Sum

function p81(){

  loadStrings("p081_matrix.txt",p81_read); 

}

function p81_read(result){

  //turn txt file into 2d array

  for(let i = 0; i < result.length; i++){

    result[i] = int(result[i].split(","));    

  }

  const len = result.length - 1;

  for(let i = len; i >= 0; i--){

    for(let j = len; j >= 0; j--){

      if(i < len && j < len){

        result[i][j] += min(result[i][j+1],result[i+1][j]);

      }else if(i < len){

        result[i][j] += result[i+1][j];

      }else if(j < len){

        result[i][j] += result[i][j+1];

      }

    }

  }

  console.log(result)

  console.log(`Min path: ${result[0][0]}`);

}

//Path Sum

function p82(){

  loadStrings("p082_matrix.txt",p82_read); 

}

function p82_read(result){

  const len = result.length;

  //turn txt file into 2d array

  for(let i = 0; i < len; i++){

    result[i] = int(result[i].split(","));

  }

  //transpose that bad boi using fancy stuff

  let trans = result[0].map((_, colIndex) => result.map(row => row[colIndex]));

  //loop through cols

  for(let i = 1; i < len; i++){

    let sumUp = [];

    let sumDown = [];

    //loop through column entries top to bot

    for(let j = 0; j < len; j++){

      //edge case bot - only compute left + self

      if(j == 0){

        sumUp[j] = trans[i][j] + trans[i-1][j];

      }else{ //otherwise compute min of left + self and down + left

        sumUp[j] = trans[i][j] + min(trans[i-1][j],sumUp[j-1]);

      }

    }

    //loop through entries bot to top

    for(let j = len - 1; j >= 0; j--){

      //edge case up - only compute left + self

      if(j == len - 1){

        sumDown[j] = trans[i][j] + trans[i-1][j];

      }else{ //otherwise compute min of left + self and up + left

        sumDown[j] = trans[i][j] + min(trans[i-1][j],sumDown[j+1]);

      }

    } 

    //update matrix with smallest value

    for(let j = 0; j < len; j++){

      trans[i][j] = min(sumUp[j],sumDown[j]);

    }

  }

  //find min value of last col 

  console.log(`Min path: ${min(trans[len-1])}`);

}

//Path Sum -- Incomplete! 

function p83(){

  loadStrings("p083_matrix.txt",p83_read); 

}

function p83_read(result){

  const len = result.length;

  //turn txt file into 2d array

  for(let i = 0; i < len; i++){

    result[i] = int(result[i].split(","));

  }

  //transpose that bad boi using fancy stuff

  let trans = result[0].map((_, colIndex) => result.map(row => row[colIndex]));

  console.log(trans)

  //loop through cols

  for(let i = 1; i < len; i++){

    let sumUp = [];

    let sumDown = [];

    //loop through column entries top to bot

    for(let j = 0; j < len; j++){

      //edge case bot - only compute left + self

      if(j == 0){

        sumUp[j] = trans[i][j] + trans[i-1][j];

      }else{ //otherwise compute min of left + self and down + left

        sumUp[j] = trans[i][j] + min(trans[i-1][j],sumUp[j-1]);

      }

    }

    //loop through entries bot to top

    for(let j = len - 1; j >= 0; j--){

      //edge case up - only compute left + self

      if(j == len - 1){

        sumDown[j] = trans[i][j] + trans[i-1][j];

      }else{ //otherwise compute min of left + self and up + left

        sumDown[j] = trans[i][j] + min(trans[i-1][j],sumDown[j+1]);

      }

    } 

    //update matrix with smallest value

    for(let j = 0; j < len; j++){

      trans[i][j] = min(sumUp[j],sumDown[j]);

    }

    console.log(trans[i]);

  }

  console.log(`Min path: ${trans[len-1][len-1]}`);

}