[HAI] week3 two sum withou hashsum

https://leetcode.com/problems/two-sum-ii-input-array-is-sorted

lib/twoSum/index.ts

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+import { twoSum } from "./twoSum";
+
+export default twoSum;

lib/twoSum/readme.md

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+# [twoSum](https://leetcode.com/problems/two-sum-ii-input-array-is-sorted)
+
+## описание задачи
+
+Given a 1-indexed array of integers numbers that is already sorted in non-decreasing order, find two numbers such that they add up to a specific target number. Let these two numbers be numbers[index1] and numbers[index2] where 1 <= index1 < index2 <= numbers.length.
+
+Return the indices of the two numbers, index1 and index2, added by one as an integer array [index1, index2] of length 2.
+
+The tests are generated such that there is exactly one solution. You may not use the same element twice.
+
+Your solution must use only constant extra space.
+
+ 
+
+Example 1:
+
+- Input: numbers = [2,7,11,15], target = 9
+- Output: [1,2]
+- Explanation: The sum of 2 and 7 is 9. Therefore, index1 = 1, index2 = 2. We return [1, 2].
+
+Example 2:
+
+- Input: numbers = [2,3,4], target = 6
+- Output: [1,3]
+- Explanation: The sum of 2 and 4 is 6. Therefore index1 = 1, index2 = 3. We return [1, 3].
+
+Example 3:
+
+- Input: numbers = [-1,0], target = -1
+- Output: [1,2]
+- Explanation: The sum of -1 and 0 is -1. Therefore index1 = 1, index2 = 2. We return [1, 2].
+ 
+
+Constraints:
+
+2 <= numbers.length <= 3 * 104
+-1000 <= numbers[i] <= 1000
+numbers is sorted in non-decreasing order.
+-1000 <= target <= 1000
+The tests are generated such that there is exactly one solution.
+
+## тест кейсы
+
+```ts
+describe("twoSum", () => {
+
+  it("[2,7,11,15] 9 => [1,2]", () => {
+    expect(twoSum([2, 7, 11, 15], 9)).toEqual([1, 2]);
+  });
+
+  it("[2,3,4] 6 => [1,3]", () => {
+    expect(twoSum([2, 3, 4], 6)).toEqual([1, 3]);
+  });
+
+  it("[-1, 0] -1 => [1, 2]", () => {
+    expect(twoSum([-1, 0], -1)).toEqual([1, 2]);
+  });
+
+  it("[5,25,75] 100 => [2,3]", () => {
+    expect(twoSum([5, 25, 75], 100)).toEqual([2, 3]);
+  })
+});
+```
+
+## текстовое описание решения
+
+- заводим два указателя, в начале и конце 
+- в цикле получаем по указателям значение и складываем
+- если сумма больше таргет двигаем правый указатель
+- если сумма меньше таргет двигаем левый указатель
+- если сумма равна таргет возвращаем значение указателей +1
+- если указатели сошлись а сумма не равна таргет выходим из цикла и возвращаем [-1, -1]
+
+## ассимптотическая оценка
+
+| Description | Estimation |
+| ----------- | ---------- |
+| time:       | O(n)     |
+| mem:        | O(n)     |
+
+## time
+
+| Description                                 | Time  |
+| ------------------------------------------- | ----- |
+| анализ и сбор информации                    | 11:50 |
+| обдумываение решения и формулировка решения | 08:47 |
+| имплементация                               | 20:28 |
+| исправление ошибок                          | 20:00 |
+| полное время затраченое на решение          | 01:01:07 |
+
+## журнал ошибок
+
+- не разобрался с правилами для движения указателя, какой в какой момент двигать
+- не учел условие возврата индексов + 1
+
+## code
+
+### typescript
+
+```ts
+function twoSum(numbers: number[], target: number): number[] {
+  let L = 0;
+  let R = numbers.length - 1;
+
+  while (L <= R) {
+    const curSum = numbers[L] + numbers[R];
+    if (curSum === target) return [L + 1, R + 1];
+    curSum > target ? R-- : L++;
+  }
+
+  return [-1, -1];
+};
+```
+

lib/twoSum/twoSum.test.ts

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+import { describe, it, expect } from "vitest";
+import { twoSum } from "./twoSum.ts";
+
+describe("twoSum", () => {
+
+  it("[2,7,11,15] 9 => [1,2]", () => {
+    expect(twoSum([2, 7, 11, 15], 9)).toEqual([1, 2]);
+  });
+
+  it("[2,3,4] 6 => [1,3]", () => {
+    expect(twoSum([2, 3, 4], 6)).toEqual([1, 3]);
+  });
+
+  it("[-1, 0] -1 => [1, 2]", () => {
+    expect(twoSum([-1, 0], -1)).toEqual([1, 2]);
+  });
+
+  it("[5,25,75] 100 => [2,3]", () => {
+    expect(twoSum([5, 25, 75], 100)).toEqual([2, 3]);
+  })
+});

lib/twoSum/twoSum.ts

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+export function twoSum(numbers: number[], target: number): number[] {
+  let L = 0;
+  let R = numbers.length - 1;
+
+  while (L <= R) {
+    const curSum = numbers[L] + numbers[R];
+    if (curSum === target) return [L + 1, R + 1];
+    curSum > target ? R-- : L++;
+  }
+
+  return [-1, -1];
+};