0
LearnHashing

Two Sum (Hash Drill)

Read the lesson → understand the pattern → then code. Tutor works offline (built-in teacher); optional Cursor/Gemini keys upgrade chat quality.

Topic refresher: Hashing — Pay Space, Buy Time

Replace nested loops with unordered_map / unordered_set lookups.

unordered_map<int,int> mp;
for (int i = 0; i < n; i++) {
    int need = target - nums[i];
    if (mp.count(need)) return {mp[need], i};
    mp[nums[i]] = i;
}
Hashing

Two Sum (Hash Drill)

Easy
LeetCode
1/8
EasyHashingLeetCode #1

Same Two Sum — force the hash solution

No nested loops. Prove you own unordered_map.

Examples

Example 1

Input

4 9
2 7 11 15

Output

0 1
Example 2

Input

3 6
3 2 4

Output

1 2

Stuck? Take a nudge

C++17