java: add «1219. Path with Maximum Gold»

Signed-off-by: Matej Focko <me@mfocko.xyz>

java/path-with-maximum-gold.java

@@ -0,0 +1,44 @@
+class Solution {
+  private int dfs(int[][] grid, int x, int y) {
+    int rows = grid.length;
+    int cols = grid[0].length;
+
+    // BASE: out of bounds
+    if (y < 0 || y >= rows || x < 0 || x >= cols) {
+      return 0;
+    }
+
+    // BASE: nothing to collect
+    if (grid[y][x] == 0) {
+      return 0;
+    }
+
+    int found = 0;
+
+    int current = grid[y][x];
+
+    grid[y][x] = 0;
+    for (int d = -1; d <= 1; d += 2) {
+      found = Math.max(found, dfs(grid, x + d, y));
+      found = Math.max(found, dfs(grid, x, y + d));
+    }
+    grid[y][x] = current;
+
+    return found + current;
+  }
+
+  public int getMaximumGold(int[][] grid) {
+    int rows = grid.length;
+    int cols = grid[0].length;
+
+    int maxGoldFound = 0;
+    for (int i = 0; i < rows * cols; ++i) {
+      int y = i / cols;
+      int x = i % cols;
+
+      maxGoldFound = Math.max(maxGoldFound, dfs(grid, x, y));
+    }
+
+    return maxGoldFound;
+  }
+}