Invisible Island
Hard
matrix
island-counting
dfs
border-detection
Problem Description
In a matrix of 0s (water) and 1s (land), find islands that are completely surrounded by water with no border contact. Islands touching matrix borders don't count.
Input Format
First line: m n. Next m lines: matrix with 0s and 1s.
Output Format
Number of invisible islands (completely surrounded, no border contact).
Constraints
• 1 ≤ m, n ≤ 100
• Matrix contains only 0s and 1s
• Islands connected by 4-directions (up, down, left, right)
• Islands touching borders are not invisible
• Count separate invisible islands
Sample Input/Output
Input:
4 4 0 0 0 0 0 1 1 0 0 1 0 0 0 0 0 0
Output:
1
Explanation
Island at positions (1,1), (1,2), (2,1) is completely surrounded by water and doesn't touch borders.
Solution Hints
125
Points
Points
3000ms
Time Limit
Time Limit
256MB
Memory Limit
Memory Limit
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