TwoSum

<aside> 💡 Sort. While left is less than right: calculate sum, move left pointer for bigger sum, move right pointer for smaller sum.

</aside>

https://leetcode.com/problems/two-sum/

function twoSum(left, right, offset = []) {
  while (left < right) {
    const sum = // calculate sum;

    if (sum === target) {
      result.push( // elements... );
      // 1. dedup..
      // 2. move both pointers...
    } else if ( // not enough ) {
      // move left...
    } else {
      // move right
    }
  }
}

• Solution

Best Time to Buy and Sell Stock

<aside> 💡 Right pointer always moves, compare value at right and left, when left becomes smaller move it to right.

</aside>

https://leetcode.com/problems/best-time-to-buy-and-sell-stock

function maxProfit(prices) {
  let left = 0;
  let right = 1;
  let maxProfit = 0;

  while (right < prices.length) {
    // going up
    if (prices[right] > prices[left]) {  // update max profit }

    // going down
    if (prices[right] < prices[left]) { // update left }

    // 💡 always moves
    right++;
  }

  return maxProfit;
}

• Solution

Contains Duplicate

<aside> 💡 Iterate and store values in hashmap. If hashmap already have it, immediately return.

</aside>