Number of distinct islands

Number of Distinct Islands II This page explains Java solution to problem Number of Distinct Islands II using Depth First Search algorithm. Problem Statement Given a non-empty 2D array grid of 0's and 1's, an island is a group of 1's (representing land) connected 4-directionally (horizontal or vertical.) You may assume all four edges of the grid are surrounded by water. Count the number of distinct islands. An island is considered to be the same as another if they have the same shape, or have the same shape after rotation ( 90, 180, or 270 degrees only) or reflection (left/right direction or up/down direction). Example 1: Input: 11000 10000 00001 00011 Output: 1 Explanation: Island 1: 11 1 And Island 2: Â Â 1 11 Are considered same shaped island, so return 1 Solution If you have any suggestions in below code, please package com.vc.hard; import java.util.*; class NumberOfDistinctIslandsIi Time Complexity O(RC 2) Where R is number of rows C is number of cols Space Complexity O(RC) Where R is number of rows C is number of cols

Leetcode 694. Number of Distinct Islands (Python) Related Topic Description Given a non-empty 2D array grid of 0’s and 1’s, an island is a group of 1’s (representing land) connected 4-directionally (horizontal or vertical.) You may assume all four edges of the grid are surrounded by water. Count the number of distinct islands. An island is considered to be the same as another if and only if one island can be translated (and not rotated or reflected) to equal the other. Sample I/O Example 1 1 11 are considered different island shapes, because we do not consider reflection / rotation. Note: The length of each dimension in the given grid does not exceed 50. Methodology This question can be solved by Depth First Search and It is similar with question To find the number of distince islands, we need to record the shape of each island. If two islands with same shape then they are not distinct and count as 1 island. To find the island, we will use dfs and it will be same as question 200 to find the number of islands. Code def numDistinctIslands ( self , grid : List [ List [ int ]]) -> int : row = len ( grid ) col = len ( grid [ 0 ]) shapes = set () directions = [( - 1 , 0 ),( 0 , 1 ),( 1 , 0 ),( 0 , - 1 )] visited = set () def dfs ( x , y , pos , island_direction ): for dx , dy in directions : nx , ny = x + dx , y + dy if 0 <= nx < row and 0 <= ny < col and grid [ nx ][ ny ] and ( nx , ny ) not in visited : temp_direction = ( pos [ 0 ] + dx , pos [ 1 ] + dy ) visited . add (( nx ,...

Close Save Hard Find the number of distinct Islands OR connected components. Objective: Given a 2d grid map of '1's (land) and '0's (water), count the number of distinct or unique islands. Island: An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. Assume all four edges of the grid are all surrounded by water. Given such a grid, write an algorithm to find the number of distinct islands in it. This problem can also be also as find the number of distinct or unique connected components in the given graph. Example: Example 1: Input: 11110 11010 11000 00000 No of distinct Islands: 1 Example 2: Input: 11000 11011 00100 00011 No of distinct Islands: 2 Example 3: Input: 11011 10100 00110 10000 11011 No of distinct Islands: 3 Approach: Earlier we have seen the problem - Use Depth-First Search If all the nodes in the grid are connected then after DFS all the nodes will be visited and there will be only one Island in the grid. If there are more islands in the grid we need to multiple DFS to visit them all. So Number of Islands will be equal to the number of DFS required to visit all isLands (1's) How to determine if two islands are identical: If coordinates in two islands form an identical shape or structure. The coordinates of both the islands can be at a different location. See the example below Steps: • Start the DFS from the node with value 1 (consider this node as start node of the island, store its coordinates in (start_x, sta...

Problem Statement: Given a boolean 2D matrix grid of size N x M. You have to find the number of distinct islands where a group of connected 1s (horizontally or vertically) forms an island. Two islands are considered to be distinct if and only if one island is equal to another (not rotated or reflected). Examples: Example 1: Input: Output: 1 Explanation: Island at the top left corner is the same as the island at the bottom right corner. Example 2: Input: Output: 3 Explanation: Island at the top right corner is the same as the island at the bottom left corner. Solution Disclaimer: Don’t jump directly to the solution, try it out yourself first. Intuition:. Consider the following example, the two islands in the first figure might look identical but they are rotated so you can’t say they are the same, hence 2 distinct islands; whereas in the second figure, both islands are the same so only 1 distinct island; resulting in overall 3 distinct islands. Consider another example, the two islands in the first figure and another two islands in the second figure are the same, hence total of 2 distinct islands. Depending on the shape of the island formed, we count the number of islands. The question arises how to store these shapes? We can store the shapes in a set data structure, then the set will return unique islands. We can store the coordinates in a vector or a list. But how to figure out if the coordinates stored in the set data structure are identical?We can call one of the starti...

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• Login • Category • Java • JSP • iOS • HTML • Android • Python • C Programming • C++ Programming • C# • PHP • CSS • Javascript • jQuery • SAP • SAP HANA • Data Structure • RDBMS • MySQL • Mathematics • 8085 Microprocessor • Operating System • Digital Electronics • Analysis of Algorithms • Mobile Development • Front End • Web Development • Selenium • MongoDB • Computer Network • General Topics Suppose we have a 2d binary matrix, we have to find the number of distinct islands in the given matrix. Here 1 represents land and 0 represents water, so an island is a set of 1s that are close and whose perimeter is surrounded by water. Here two islands are unique if their shapes are different. So, if the input is like 1 0 0 0 0 1 0 1 0 1 0 1 1 0 1 0 0 1 0 0 1 0 0 0 0 1 1 0 1 1 then the output will be 4 (distinct islands are in different color). To solve this, we will follow these steps − • Define a function dfs() . This will take i, j, k, l • mat[i, j] := 0 • insert pair (i − k, j − l) at the end of shape • if i + 1 = 0 and mat[i − 1, j] is 1, then • dfs(i − 1, j, k, l) • if j − 1 >= 0 and mat[i, j − 1] is 1, then • dfs(i, j − 1, k, l) • From the main method do the following − • cnt := 0 • shapes := a new set • for i in range 0 to row count of mat, do • for j in range 0 to column count of mat, do • if mat[i, j] is 1, then • shape := a new list • dfs(i, j, i, j) • if shape is not in shapes, then • cnt := cnt + 1 • insert shape into shapes • return cnt Let us see the following implem...