3Sum

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

Topic refresher: Two Pointers — Two Indices, One Rule

Move left/right based on a condition instead of checking all pairs.

int L = 0, R = n - 1;
while (L < R) {
    int sum = a[L] + a[R];
    if (sum == target) { L++; R--; }
    else if (sum < target) L++;
    else R--;
}

Medium

3/7

MediumTwo PointersLeetCode #15

Sort. Fix one index; two-sum the rest with two pointers. Skip duplicates.

Examples

Example 1

Input

6
-1 0 1 2 -1 -4

Output

-1 -1 2 | -1 0 1

Example 2

Input

3
0 1 1

Output

C++17Autosaves