LeetCode in Kotlin

1219. Path with Maximum Gold

Medium

In a gold mine grid of size m x n, each cell in this mine has an integer representing the amount of gold in that cell, 0 if it is empty.

Return the maximum amount of gold you can collect under the conditions:

• Every time you are located in a cell you will collect all the gold in that cell.
• From your position, you can walk one step to the left, right, up, or down.
• You can’t visit the same cell more than once.
• Never visit a cell with 0 gold.
• You can start and stop collecting gold from any position in the grid that has some gold.

Example 1:

Input: grid = [[0,6,0],[5,8,7],[0,9,0]]

Output: 24

Explanation:

[[0,6,0], 
 [5,8,7], 
 [0,9,0]] 
Path to get the maximum gold, 9 -> 8 -> 7.

Example 2:

Input: grid = [[1,0,7],[2,0,6],[3,4,5],[0,3,0],[9,0,20]]

Output: 28

Explanation:

[[1,0,7], 
 [2,0,6], 
 [3,4,5], 
 [0,3,0], 
 [9,0,20]] 
Path to get the maximum gold, 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7.

Constraints:

• m == grid.length
• n == grid[i].length
• 1 <= m, n <= 15
• 0 <= grid[i][j] <= 100
• There are at most 25 cells containing gold.

Solution

class Solution {
    private var maxGold = 0
    fun getMaximumGold(grid: Array<IntArray>): Int {
        for (i in grid.indices) {
            for (j in grid[0].indices) {
                if (grid[i][j] != 0) {
                    val g = grid[i][j]
                    grid[i][j] = 0
                    gold(grid, i, j, g)
                    grid[i][j] = g
                }
            }
        }
        return maxGold
    }

    private fun gold(grid: Array<IntArray>, row: Int, col: Int, gold: Int) {
        if (gold > maxGold) {
            maxGold = gold
        }
        if (row > 0 && grid[row - 1][col] != 0) {
            val currGold = grid[row - 1][col]
            grid[row - 1][col] = 0
            gold(grid, row - 1, col, gold + currGold)
            grid[row - 1][col] = currGold
        }
        if (col > 0 && grid[row][col - 1] != 0) {
            val currGold = grid[row][col - 1]
            grid[row][col - 1] = 0
            gold(grid, row, col - 1, gold + currGold)
            grid[row][col - 1] = currGold
        }
        if (row < grid.size - 1 && grid[row + 1][col] != 0) {
            // flag=false;
            val currGold = grid[row + 1][col]
            grid[row + 1][col] = 0
            gold(grid, row + 1, col, gold + currGold)
            grid[row + 1][col] = currGold
        }
        if (col < grid[0].size - 1 && grid[row][col + 1] != 0) {
            val currGold = grid[row][col + 1]
            grid[row][col + 1] = 0
            gold(grid, row, col + 1, gold + currGold)
            grid[row][col + 1] = currGold
        }
    }
}

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