Find All Groups of Farmland

LeetCode – 1992. Find All Groups of Farmland
Approach

• WE FIRST CREATE A FARMER FUNCTION THAT WE WILL CALL RECURSIVELY
• IT WILL CHECK IF THE LAND WE ARE TRYING TO ACCESS IS OUT OF BOUNDS OR IS NOT A FIELD IN WHICH CASE IT WILL JUST RETURN BACK
• ONCE WE HAVE A FIELD THAT IS IN BOUNDS AND NOT ZERO
• WE MARK IT ZERO TO KNOW THAT WE HAVE ALREADY VISITED THIS POINT AND NEED NOT CONSIDER IT AGAIN
• NOW IN OUR ARRAY CONTAINING THE LEFT MOST POINTS AND RIGHT MOST POINTS
• INITIALLY THE POINT IN LAND THAT WE FIRST ENCOUNTER A FIELD LEFT MOST AND RIGHT MOST POINTS ARE ITSELF ONLY
• NOW IN THE RECURSIVE FUNCTION WE COMPARE OUR FIELD COORDINATED TO THE MIN AND MAX OF THE ORIGINAL COORDINATES AND MODIFY THEM ACCORDINGLY
• LEFT MOST POINT WILL BE THE LEAST POSSIBLE COORDINATE
• RIGHT MOST POINT WILL BE THE MAX POSSIBLE COORDINTE
• JUST RETURN THE OUTPUT ARRAY

/** * @param {number[][]} land * @return {number[][]} */
var findFarmland = function (land) { let rows = land.length; let cols = land[0].length; let endRow = 0; let endCol = 0; let result = []; callDFS = (i, j) => { if (i < 0 || j < 0 || i >= rows || j >= cols || land[i][j] == 0) { return; } endRow = Math.max(endRow, i); endCol = Math.max(endCol, j); land[i][j] = 0; callDFS(i + 1, j); callDFS(i - 1, j); callDFS(i, j + 1); callDFS(i, j - 1); } for (let i = 0; i < rows; i++) { for (let j = 0; j < cols; j++) { if (land[i][j] === 1) { endRow = 0; endCol = 0; // call recursion callDFS(i, j); result.push([i, j, endRow, endCol]); } } } return result; }; console.log(findFarmland([[1, 0, 0], [0, 1, 1], [0, 1, 1]]))