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[11/14] 947. Most Stones Removed with Same Row or Column
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Medium
4072582Add to ListShareOn a 2D plane, we place n
stones at some integer coordinate points. Each coordinate point may have at most one stone.
A stone can be removed if it shares either the same row or the same column as another stone that has not been removed.
Given an array stones
of length n
where stones[i] = [xi, yi]
represents the location of the ith
stone, return the largest possible number of stones that can be removed.
Example 1:
Input: stones = [[0,0],[0,1],[1,0],[1,2],[2,1],[2,2]] Output: 5 Explanation: One way to remove 5 stones is as follows: 1. Remove stone [2,2] because it shares the same row as [2,1]. 2. Remove stone [2,1] because it shares the same column as [0,1]. 3. Remove stone [1,2] because it shares the same row as [1,0]. 4. Remove stone [1,0] because it shares the same column as [0,0]. 5. Remove stone [0,1] because it shares the same row as [0,0]. Stone [0,0] cannot be removed since it does not share a row/column with another stone still on the plane.
Example 2:
Input: stones = [[0,0],[0,2],[1,1],[2,0],[2,2]] Output: 3 Explanation: One way to make 3 moves is as follows: 1. Remove stone [2,2] because it shares the same row as [2,0]. 2. Remove stone [2,0] because it shares the same column as [0,0]. 3. Remove stone [0,2] because it shares the same row as [0,0]. Stones [0,0] and [1,1] cannot be removed since they do not share a row/column with another stone still on the plane.
Example 3:
Input: stones = [[0,0]] Output: 0 Explanation: [0,0] is the only stone on the plane, so you cannot remove it.
Constraints:
1 <= stones.length <= 1000
0 <= xi, yi <= 104
- No two stones are at the same coordinate point.
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Submissions
259,960
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Runtime: 356 ms, faster than 64.53% of Python3 online submissions for Most Stones Removed with Same Row or Column.
Memory Usage: 18.2 MB, less than 5.27% of Python3 online submissions for Most Stones Removed with Same Row or Column.
Memory Usage: 18.2 MB, less than 5.27% of Python3 online submissions for Most Stones Removed with Same Row or Column.
from collections import defaultdict
class Solution:
def removeStones(self, stones: List[List[int]]) -> int:
rowdic = defaultdict(list)
coldic = defaultdict(list)
for row, col in stones:
rowdic[row].append((row,col))
coldic[col].append((row,col))
visited = set()
def dfs(r,c):
visited.add((r,c))
for row, col in rowdic[r]:
if (row,col) not in visited:
dfs(row,col)
for row, col in coldic[c]:
if (row,col) not in visited:
dfs(row,col)
island = 0
for row, col in stones:
if (row,col) not in visited:
dfs(row,col)
island += 1
return len(stones) - island