/*
Good morning! Here's your coding interview problem for today.

This problem was asked by Stripe.

Given an array of integers, find the first missing positive integer in linear time and constant space. In other words, find the lowest positive integer that does not exist in the array. The array can contain duplicates and negative numbers as well.

For example, the input [3, 4, -1, 1] should give 2. The input [1, 2, 0] should give 3.

You can modify the input array in-place.
*/
#include <iostream>
using namespace std;

int calcMissing(int* input, int size)
{
	int sum = 0;
	int n = 1; //add one to account for missing value
	for(int i = 0; i < size; i++)
	{
	if(input[i] > 0)
	{
	sum += input[i];
	n++;
	}
	}

	//If no numbers higher than 0, answer is 1
	if(sum == 0)
	return 1;

	return (n*(n+1)/2) - sum; //Formula is expectedSum - actualSum
	/* expectedSum = n*(n+1)/2, the formula for sum(1, n) */
}

int main()
{

	cout << calcMissing(new int[4]{3, 4, -1, 1}, 4) << endl;
	cout << calcMissing(new int[3]{1, 2, 0}, 3) << endl;

	//No positive numbers
	cout << calcMissing(new int[1]{0}, 1) << endl;
}

var invertTree = function(root) {
    const reverseNode = node => {
        if (node == null) {
            return null
        }
        reverseNode(node.left);
        reverseNode(node.right);
        let holdLeft = node.left;
        node.left = node.right;
        node.right = holdLeft;
        return node;
    }

    return reverseNode(root);
};

const MongoClient = require('mongodb').MongoClient;
const assert = require('assert');

// Connection URL
const url = 'mongodb://localhost:27017';

// Database Name
const dbName = 'myproject';

// Use connect method to connect to the server
MongoClient.connect(url, function(err, client) {
  assert.equal(null, err);
  console.log("Connected successfully to server");

  const db = client.db(dbName);

  client.close();
});

my_list = ["blue", "red", "green"]

#1- Using sort or srted directly or with specifc keys
my_list.sort() #sorts alphabetically or in an ascending order for numeric data 
my_list = sorted(my_list, key=len) #sorts the list based on the length of the strings from shortest to longest. 
# You can use reverse=True to flip the order

#2- Using locale and functools 
import locale
from functools import cmp_to_key
my_list = sorted(my_list, key=cmp_to_key(locale.strcoll))

# Python program for implementation of Bubble Sort

def bubbleSort(arr):
	n = len(arr)

	# Traverse through all array elements
	for i in range(n-1):
	# range(n) also work but outer loop will repeat one time more than needed.

		# Last i elements are already in place
		for j in range(0, n-i-1):

			# traverse the array from 0 to n-i-1
			# Swap if the element found is greater
			# than the next element
			if arr[j] > arr[j+1] :
				arr[j], arr[j+1] = arr[j+1], arr[j]

# Driver code to test above
arr = [64, 34, 25, 12, 22, 11, 90]

bubbleSort(arr)

print ("Sorted array is:")
for i in range(len(arr)):
	print ("%d" %arr[i]),

const getFollowers = async (req: Request, res: Response) => {
  try {
    const username = req.params.username || '';

    const user = await User.findUnique({
      where: { username },
      include: { followedBy: true },
    });

    if (!user) {
      res.status(404).json({
        error: 'User could not be found',
      });
      return;
    }

    const followers = user.followedBy.map(followedBy => {
      return {
        followerId: followedBy.followerId,
      };
    });

    const followersCount = followers.length;

    res.json({ followersCount: followersCount, followers });
  } catch (error) {
    console.error('getFollowers() error: ', error);
    res.status(500).json({
      error: `There was an error fetching followers for user with username "${req.params.username}", please try again later`,
    });
  }
};

const getFollowing = async (req: Request, res: Response) => {
  try {
    const username = req.params.username || '';

    const user = await User.findUnique({
      where: { username },
      include: { following: true },
    });

    if (!user) {
      res.status(404).json({
        error: 'User could not be found',
      });
      return;
    }

    const following = user.following.map(following => {
      return {
        followingId: following.followingId,
      };
    });

    const followingCount = following.length;

    res.json({ followingCount: followingCount, following });
  } catch (error) {
    console.error('getFollowing() error: ', error);
    res.status(500).json({
      error: `There was an error fetching who is following "${req.params.username}", please try again later`,
    });
  }
};

const followUser = async (req: Request, res: Response) => {
  try {
    const username = req.params.username || '';

    const user = await User.findUnique({
      where: { username },
    });

    if (!user) {
      res.status(404).json({
        error: 'User could not be found',
      });
      return;
    }

    // dont allow a user to follow themselves
    if (req.user.id === user.id) {
      res.status(400).json({ error: 'You cannot follow yourself' });
      return;
    }

    //check if a follow relationship already exists
    const followrelationship = await prisma.follows.findUnique({
      where: {
        followerId_followingId: {
          followerId: req.user.id,
          followingId: user.id,
        },
      },
    });

    // check if the follow relationship already exists
    if (followrelationship) {
      res.status(400).json({ error: 'You are already following this user' });
      return;
    }

    // create the follow relationship
    const follow = await prisma.follows.create({
      data: {
        followerId: req.user.id,
        followingId: user.id,
      },
    });

    res.json({ follow });
  } catch (error) {
    console.error('followUser() error: ', error);
    res.status(500).json({
      error: `There was an error following "${req.params.username}", please try again later`,
    });
  }
};

const unfollowUser = async (req: Request, res: Response) => {
  try {
    const username = req.params.username || '';

    const user = await User.findUnique({
      where: { username },
    });

    if (!user) {
      res.status(404).json({
        error: 'User could not be found',
      });
      return;
    }

    // dont allow a user to unfollow themselves
    if (req.user.id === user.id) {
      res.status(400).json({ error: 'You cannot unfollow yourself' });
      return;
    }

    //check if a follow relationship already exists
    const followrelationship = await prisma.follows.findUnique({
      where: {
        followerId_followingId: {
          followerId: req.user.id,
          followingId: user.id,
        },
      },
    });

    // check if the follow relationship already exists
    if (!followrelationship) {
      res.status(400).json({ error: 'You are not following this user' });
      return;
    }

    // delete the follow relationship
    const follow = await prisma.follows.delete({
      where: {
        followerId_followingId: {
          followerId: req.user.id,
          followingId: user.id,
        },
      },
    });

    res.json({ follow });
  } catch (error) {
    console.error('unfollowUser() error: ', error);
    res.status(500).json({
      error: `There was an error unfollowing "${req.params.username}", please try again later`,
    });
  }
};

const mongoose = require('mongoose')

const UserSchema = new mongoose.Schema({
	username: {
	type: String,
	required: true
	},
	email: {
	type: String,
	unique: true,
	required: true
	},
	password: {
	type: String,
	required: true
	},
	date: {
	type: Date,
	default: Date.now
	}
})

module.exports = User = mongoose.model('user', UserSchema)

$base-color: #036;

@for $i from 1 through 3 {
  ul:nth-child(3n + #{$i}) {
    background-color: lighten($base-color, $i * 5%);
  }
}