Java Exercises: Find possible unique paths considering some obstacles, from top-left corner to bottom-right corner of a specified grid

Last update on August 09 2022 03:31:01 (UTC/GMT +8 hours)

Java Basic: Exercise-137 with Solution

Write a Java program to find possible unique paths considering some obstacles, from top-left corner to bottom-right corner of a given grid (m x n).

Note: You can move either down or right at any point in time and an obstacle and empty space is marked as 1 and 0 respectively in the grid. Sample grid:
int[][] obstacle_Grid ={
{0, 0, 0},
{0, 1, 0},
{0, 0, 0},
};

Sample Solution:

Java Code:

public class Solution {
    public static int uniquePaths_With_obstacle_Grid(int[][] obstacle_Grid) {
		int m = obstacle_Grid.length;
		if (m <= 0) {
			return 0;
		}
		int n = obstacle_Grid[0].length;
		if (n <= 0) {
			return 0;
		}
		int[][] dp = new int[m + 1][n + 1];
		dp[m][n - 1] = 1;
		for (int i = m - 1; i >= 0; --i) {
			for (int j = n - 1; j >= 0; --j) {
				dp[i][j] = (obstacle_Grid[i][j] == 0) ? dp[i + 1][j] + dp[i][j + 1] : 0;
			}
		}
		return dp[0][0];
	}
    
  public static void main(String[] args) {
		int[][] obstacle_Grid ={
                              {0, 0, 0}, 
                              {0, 1, 0}, 
                              {0, 0, 0}, 
                              };
		System.out.println("Unique paths from top-left corner to bottom-right corner of the said grid (considering some obstacles): "+uniquePaths_With_obstacle_Grid(obstacle_Grid));
	}		
}

Sample Output:

Unique paths from top-left corner to bottom-right corner of the said grid (considering some obstacles): 2s

Flowchart:

Java Code Editor:

Company: Bloomberg

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Java: Tips of the Day

countOccurrences

Counts the occurrences of a value in an array.

Use Arrays.stream().filter().count() to count total number of values that equals the specified value.

public static long countOccurrences(int[] numbers, int value) { return Arrays.stream(numbers) .filter(number -> number == value) .count(); }

Ref: https://bit.ly/3kCAgLb