Sliding Window — Live Range
Maintain [L,R] that satisfies a constraint; answer from length/sum/counts.
Suno.Stringdihai.Sabselambisubstringchahiyejismekoicharacterdobaarnaaaye.
Listen. You get a string. Find the longest substring with no repeated character.
0:00 / 1:02
When to use this
- Longest/shortest subarray/substring
- Fixed k
- At most K zeros/distinct
C++ template
int L = 0;
for (int R = 0; R < n; R++) {
// add s[R]
while (/* invalid */) { /* remove s[L] */ L++; }
// update answer
}Dry run
"abcabcbb" → max unique window length 3.
Pitfalls
- Answer update timing
- R-L+1 off-by-one
- Subsequence vs subarray
Say this in the interview
Each index enters/leaves once → O(n).
Problems in this topic (6)
Each opens teach-first (animated when available), then the code panel.