Leetcode #1318: Minimum Flips to Make a OR b Equal to c
In this guide, we solve Leetcode #1318 Minimum Flips to Make a OR b Equal to c in Python and focus on the core idea that makes the solution efficient.
You will see the intuition, the step-by-step method, and a clean Python implementation you can use in interviews.
Problem Statement
Given 3 positives numbers a, b and c. Return the minimum flips required in some bits of a and b to make ( a OR b == c ).
Quick Facts
- Difficulty: Medium
- Premium: No
- Tags: Bit Manipulation
Intuition
The problem structure lets us track state with bitwise operations.
Bit operations are constant time and avoid extra memory.
Approach
Apply XOR/AND/OR and shifts to maintain the required invariant.
Aggregate the result in a single pass.
Steps:
- Identify a bitwise invariant.
- Combine values with bit operations.
- Return the aggregated result.
Example
Input: a = 2, b = 6, c = 5
Output: 3
Explanation: After flips a = 1 , b = 4 , c = 5 such that (a OR b == c)
Python Solution
class Solution:
def minFlips(self, a: int, b: int, c: int) -> int:
ans = 0
for i in range(32):
x, y, z = a >> i & 1, b >> i & 1, c >> i & 1
ans += x + y if z == 0 else int(x == 0 and y == 0)
return ans
Complexity
The time complexity is , where is the maximum value of the numbers in the problem. The space complexity is .
Edge Cases and Pitfalls
Watch for boundary values, empty inputs, and duplicate values where applicable. If the problem involves ordering or constraints, confirm the invariant is preserved at every step.
Summary
This Python solution focuses on the essential structure of the problem and keeps the implementation interview-friendly while meeting the constraints.