Remove All Ones With Row and Column Flips II — LeetCode 2174 Python Solution
MediumLeetCode PremiumBit ManipulationBreadth-First SearchArrayMatrix
- Problem
- #2174
- Pattern
- Bit Manipulation
- Reading time
- 5 min
- Source
- leetcode.com
The problem
You are given a 0-indexed m x n binary matrix grid. In one operation, you can choose any i and j that meet the following conditions: 0 <= i < m 0 <= j < n grid[i][j] == 1 and change the values of all cells in row i and column j to zero.
Example
- Input
- grid = [[1,1,1],[1,1,1],[0,1,0]]
- Output
- 2
- Explanation
- In the first operation, change all cell values of row 1 and column 1 to zero.
Python solution
Python
class Solution:
def removeOnes(self, grid: List[List[int]]) -> int:
m, n = len(grid), len(grid[0])
state = sum(1 << (i * n + j) for i in range(m) for j in range(n) if grid[i][j])
q = deque([state])
vis = {state}
ans = 0
while q:
for _ in range(len(q)):
state = q.popleft()
if state == 0:
return ans
for i in range(m):
for j in range(n):
if grid[i][j] == 0:
continue
nxt = state
for r in range(m):
nxt &= ~(1 << (r * n + j))
for c in range(n):
nxt &= ~(1 << (i * n + c))
if nxt not in vis:
vis.add(nxt)
q.append(nxt)
ans += 1
return -1Complexity
| Measure | Complexity |
|---|---|
| Time | O(V+E) |
| Space | O(V) auxiliary |
Pattern: Bit Manipulation
Use XOR, masks and the low-bit trick to replace whole data structures with an integer. LeetCode 2174. Remove All Ones With Row and Column Flips II is filed here because LeetCode tags it Bit Manipulation, which is the vocabulary this hub collects.
The bit manipulation guide has the Python template for the pattern and the 194 LeetCode problems that use it.
Related problems
Frequently asked questions
- How hard is LeetCode 2174. Remove All Ones With Row and Column Flips II?
- LeetCode 2174. Remove All Ones With Row and Column Flips II is rated Medium on LeetCode.
- What is the time complexity of LeetCode 2174. Remove All Ones With Row and Column Flips II?
- The Python solution on this page runs in O(V+E).
- What is the space complexity of LeetCode 2174. Remove All Ones With Row and Column Flips II?
- The Python solution on this page uses O(V) auxiliary space.
- What topics does LeetCode 2174. Remove All Ones With Row and Column Flips II cover?
- LeetCode 2174. Remove All Ones With Row and Column Flips II is tagged Bit Manipulation, Breadth-First Search, Array and Matrix on LeetCode.
- Is LeetCode 2174. Remove All Ones With Row and Column Flips II a premium problem?
- Yes. LeetCode 2174. Remove All Ones With Row and Column Flips II is a LeetCode Premium problem, so the full statement and test cases require a paid LeetCode subscription.