Top groww interview questions

function findMax(arr) {
  return Math.max.apply(null, arr);
}

function findMin(arr) {
  return Math.min.apply(null, arr);
}

function reverseString(str) {
  return str.split('').reverse().join('');
}

function isPalindrome(str) {
  return str === str.split('').reverse().join('');
}

function findFirstDuplicate(arr) {
  let seen = new Set();
  for (let i = 0; i < arr.length; i++) {
    if (seen.has(arr[i])) {
      return arr[i];
    }
    seen.add(arr[i]);
  }
  return null;
}

function findMissingNumber(arr) {
  let n = arr.length;
  let sum = (n * (n + 1)) / 2;
  let actualSum = arr.reduce((a, b) => a + b, 0);
  return sum - actualSum;
}

function maxSubarraySum(arr) {
  let maxSum = -Infinity;
  let currentSum = 0;
  for (let i = 0; i < arr.length; i++) {
    currentSum = Math.max(arr[i], currentSum + arr[i]);
    maxSum = Math.max(maxSum, currentSum);
  }
  return maxSum;
}

function minWindowSubstring(str, target) {
  let targetCount = {};
  for (let char of target) {
    if (!targetCount[char]) {
      targetCount[char] = 0;
    }
    targetCount[char]++;
  }
  let left = 0;
  let minLen = Infinity;
  let minWindow = '';
  let formed = 0;
  let windowCounts = {};
  for (let right = 0; right < str.length; right++) {
    let character = str[right];
    if (targetCount[character]) {
      if (!windowCounts[character]) {
        windowCounts[character] = 0;
      }
      windowCounts[character]++;
      if (windowCounts[character] === targetCount[character]) {
        formed++;
      }
    }
    while (left <= right && formed === Object.keys(targetCount).length) {
      let character = str[left];
      if (right - left + 1 < minLen) {
        minLen = right - left + 1;
        minWindow = str.substring(left, right + 1);
      }
      if (windowCounts[character]) {
        windowCounts[character]--;
        if (windowCounts[character] < targetCount[character]) {
          formed--;
        }
      }
      left++;
    }
  }
  return minWindow;
}

function longestCommonPrefix(strs) {
  if (!strs.length) {
    return '';
  }
  let shortest = strs.reduce((a, b) => (a.length < b.length ? a : b));
  for (let i = 0; i < shortest.length; i++) {
    let char = shortest[i];
    for (let other of strs) {
      if (other[i] !== char) {
        return shortest.substring(0, i);
      }
    }
  }
  return shortest;
}

function firstBadVersion(n) {
  let left = 1;
  let right = n;
  while (left < right) {
    let mid = left + Math.floor((right - left) / 2);
    if (isBadVersion(mid)) {
      right = mid;
    } else {
      left = mid + 1;
    }
  }
  return left;
}

function searchInsert(nums, target) {
  let left = 0;
  let right = nums.length - 1;
  while (left <= right) {
    let mid = left + Math.floor((right - left) / 2);
    if (nums[mid] === target) {
      return mid;
    } else if (nums[mid] < target) {
      left = mid + 1;
    } else {
      right = mid - 1;
    }
  }
  return left;
}

function singleNumber(nums) {
  let result = 0;
  for (let num of nums) {
    result ^= num;
  }
  return result;
}

function majorityElement(nums) {
  let count = 0;
  let candidate;
  for (let num of nums) {
    if (count === 0) {
      candidate = num;
    }
    count += num === candidate ? 1 : -1;
  }
  return candidate;
}

function findMissingNumber(arr) {
  for (let i = 0; i < arr.length - 1; i++) {
    if (arr[i + 1] - arr[i] > 1) {
      return arr[i] + 1;
    }
  }
  return null;
}

function findDuplicate(nums) {
  let tortoise = nums[0];
  let hare = nums[0];
  do {
    tortoise = nums[tortoise];
    hare = nums[nums[hare]];
  } while (tortoise !== hare);
  tortoise = nums[0];
  while (tortoise !== hare) {
    tortoise = nums[tortoise];
    hare = nums[hare];
  }
  return hare;
}