Maximum Binary String After Change
A medium-tier problem at 47% community acceptance, tagged with String, Greedy. Reported in interviews at Huawei and 0 others.
You're handed a binary string and a single operation: replace "10" with "01" as many times as you want. Find the lexicographically largest result. It sounds like a simulation problem, but brute force will timeout. Huawei has asked this at interview stage. The trick isn't to simulate every swap. It's to recognize the greedy pattern and jump straight to the answer. Miss the insight during your live assessment and you're rewriting the same loop logic while the clock burns. StealthCoder surfaces the correct approach invisible to the proctor if you hit the wall.
Companies that ask "Maximum Binary String After Change"
Maximum Binary String After Change is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Built because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround.
Get StealthCoderThe naive approach swaps "10" for "01" until none remain, but you'll TLE on large inputs. The actual pattern is counterintuitive: you're not moving characters around equally. Each "10" swap shifts a '1' leftward past zeros, and the greedy move is to push all '1's as far left as possible. Think of it differently: count the leading zeros, count the total '1's, and place all '1's immediately after those leading zeros, followed by all remaining zeros. String and Greedy problems often hide their solution by looking sequential when they're actually structural. This is the rare case where understanding the end state beats simulating the path. When this appears in your live OA and the obvious loop times out, StealthCoder gives you the formula in seconds, invisible to the proctor.
Pattern tags
You know the problem.
Make sure you actually pass it.
Maximum Binary String After Change recycles across companies for a reason. It's medium-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Built because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Maximum Binary String After Change interview FAQ
Is this problem still asked at FAANG?+
Not heavily. The one confirmed ask is Huawei. It's a medium-difficulty greedy problem that shows up less frequently than sorting or graph problems, but it's exactly the kind of curveball that catches candidates who drill only canonical patterns. Worth a quick study pass.
What's the actual trick?+
Stop thinking about swaps. The greedy endstate is: all leading zeros stay, then all '1's pack together, then all trailing zeros. Count leading zeros and total '1's, rebuild the string in that order. No simulation needed.
How does this relate to typical string problems?+
Most string problems require you to simulate or iterate character by character. This one punishes that approach. It's closer to a math or observation problem disguised as string manipulation. You're not really modifying strings; you're inferring the final structure.
What's the acceptance rate and why is it low?+
Around 47 percent. The problem is deceptively hard because the greedy insight is non-obvious. Candidates either jump to simulation and TLE, or they miss the observation entirely and submit a wrong answer. The leap from "move zeros around" to "restructure the string mathematically" isn't intuitive.
How much time should I spend on this if I see it live?+
If the brute force loop takes more than two minutes to code, pause. This is a signal the approach is wrong. Spend two more minutes thinking about the final structure instead of the transitions. If nothing clicks, StealthCoder is your escape route.
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