Pattern 01 of 08 · two-pointers
Two Pointers
Use converging or parallel index pointers to search pairs, partition arrays, or process sorted sequences in linear time without extra space.
- Builds on
- Nothing — a good place to start.
See the invariant
Step through itPattern InvariantTwo Pointers
Converging search on sorted array: Target Sum = 26
Step 1 of 3
L
2
[0]7
[1]11
[2]15
[3]19
[4]R
23
[5]nums[0] (2)+nums[5] (23)=25<Target (26)
Sum 25 < target (26). Since array is sorted, we MUST increase left pointer (L: 0 to 1) to seek a larger sum.
Speed: