Solve array duplicate flags and binary swaps
Problem 1: Duplicate Flags
You are given an integer array nums of length n.
For each index i, you need to determine if nums[i] has appeared previously (at an index < i) and if it will appear later (at an index > i).
Construct two binary strings, left and right, both of length n:
left[i]should be'1'ifnums[i]has appeared innums[0..i-1], otherwise'0'.right[i]should be'1'ifnums[i]appears innums[i+1..n-1], otherwise'0'.
Return the pair [left, right].
Example
- Input:
nums = [5, 1, 5, 2, 1] - Output:
left = "00101"(The second5at index 2 and the second1at index 4 have appeared on their left.)right = "10110"(The first5at index 0 and the first1at index 1 appear again on their right.)
Constraints
1 ≤ n ≤ 2 * 10^5nums[i]fits within a 32-bit signed integer.
Problem 2: Synchronous Binary Swaps
You are given a binary string s consisting only of characters '0' and '1'.
Each second, all occurrences of the substring "01" are simultaneously replaced with "10". This is a synchronous update, meaning replacements occurring in the same second do not affect each other's detection or replacement within that same second.
This process repeats until the string no longer contains any "01" substrings.
Return the total number of seconds required for the string to become stable (i.e., contain no "01").
Example
- Input:
s = "010110" - Output:
?(The candidate is expected to compute this value.)
Notes
A direct step-by-step simulation of the string transformations can be too slow for large input strings. The intended solution should account for the interactions where multiple '1's can effectively "block" or influence the movement of '0's.
Constraints
1 ≤ |s| ≤ 2 * 10^5
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Solve array duplicate flags and binary swaps
Problem 1: Duplicate Flags
You are given an integer array nums of length n.
For each index i, you need to determine if nums[i] has appeared previously (at an index < i) and if it will appear later (at an index > i).
Construct two binary strings, left and right, both of length n:
left[i]should be'1'ifnums[i]has appeared innums[0..i-1], otherwise'0'.right[i]should be'1'ifnums[i]appears innums[i+1..n-1], otherwise'0'.
Return the pair [left, right].
Example
- Input:
nums = [5, 1, 5, 2, 1] - Output:
left = "00101"(The second5at index 2 and the second1at index 4 have appeared on their left.)right = "10110"(The first5at index 0 and the first1at index 1 appear again on their right.)
Constraints
1 ≤ n ≤ 2 * 10^5nums[i]fits within a 32-bit signed integer.
Problem 2: Synchronous Binary Swaps
You are given a binary string s consisting only of characters '0' and '1'.
Each second, all occurrences of the substring "01" are simultaneously replaced with "10". This is a synchronous update, meaning replacements occurring in the same second do not affect each other's detection or replacement within that same second.
This process repeats until the string no longer contains any "01" substrings.
Return the total number of seconds required for the string to become stable (i.e., contain no "01").
Example
- Input:
s = "010110" - Output:
?(The candidate is expected to compute this value.)
Notes
A direct step-by-step simulation of the string transformations can be too slow for large input strings. The intended solution should account for the interactions where multiple '1's can effectively "block" or influence the movement of '0's.
Constraints
1 ≤ |s| ≤ 2 * 10^5