Add new solutions

Author: andrewbayd

src/com/andrewbayd/BinarySearchTreeLCA/Solution.java

@@ -0,0 +1,14 @@
+package com.andrewbayd.BinarySearchTreeLCA;
+
+public class Solution {
+
+    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
+        if (p.val > root.val && q.val > root.val) {
+            return lowestCommonAncestor(root.right, p, q);
+        } else if (p.val < root.val && q.val < root.val) {
+            return lowestCommonAncestor(root.left, p, q);
+        } else {
+            return root;
+        }
+    }
+}

src/com/andrewbayd/BinarySearchTreeLCA/TreeNode.java

@@ -0,0 +1,11 @@
+package com.andrewbayd.BinarySearchTreeLCA;
+
+public class TreeNode {
+    int val;
+    TreeNode left;
+    TreeNode right;
+
+    TreeNode(int x) {
+        val = x;
+    }
+}

src/com/andrewbayd/FloodFill.java

@@ -0,0 +1,51 @@
+package com.andrewbayd;
+
+import java.util.Arrays;
+
+public class FloodFill {
+
+    public int[][] floodFill(int[][] image, int sr, int sc, int newColor) {
+        int currentColor = image[sr][sc];
+        if (currentColor == newColor) {
+            return image;
+        }
+        fillPixel(image, sr, sc, currentColor, newColor);
+        return image;
+    }
+
+    private void fillPixel(int[][] image, int row, int col, int currentColor, int newColor) {
+        if (!isValidPixel(image, row, col) || image[row][col] != currentColor || image[row][col] == newColor) {
+            return;
+        }
+        image[row][col] = newColor;
+        // Filling all 4-dimensional pixels recursively
+        fillPixel(image, row-1, col, currentColor, newColor);
+        fillPixel(image, row, col+1, currentColor, newColor);
+        fillPixel(image, row+1, col, currentColor, newColor);
+        fillPixel(image, row, col-1, currentColor, newColor);
+    }
+
+    private boolean isValidPixel(int[][] image, int row, int col) {
+        int maxRow = image.length - 1;
+        int maxCol = image[0].length - 1;
+        return row >= 0 && col >= 0 && row <= maxRow && col <= maxCol;
+    }
+
+    public static void main(String[] args) {
+        int[][] image1 = {
+                {1,1,1},
+                {1,1,0},
+                {1,0,1}
+        };
+
+
+        int[][] image2 = {
+                {0,0,0},
+                {0,1,1}
+        };
+
+        FloodFill filler = new FloodFill();
+        System.out.println(Arrays.deepToString(filler.floodFill(image1, 1, 1, 2))); //-> [[2, 2, 2], [2, 2, 0], [2, 0, 1]]
+        System.out.println(Arrays.deepToString(filler.floodFill(image2, 1, 1, 1))); //-> [[0, 0, 0], [0, 1, 1]]
+    }
+}

src/com/andrewbayd/MaximumSubarray.java

@@ -0,0 +1,29 @@
+package com.andrewbayd;
+
+public class MaximumSubarray {
+
+
+    public static int maxSubArray(int[] nums) {
+        if (nums.length == 1) {
+            return nums[0];
+        }
+        int sum = 0;
+        int maxSum = nums[0];
+        for (int num : nums) {
+            sum += num;
+            if (sum > maxSum) {
+                maxSum = sum;
+            }
+            if (sum < 0) {
+                sum = 0;
+            }
+        }
+        return maxSum;
+    }
+
+    public static void main(String[] args) {
+        System.out.println(maxSubArray(new int[]{1,2,-1,-2,2,1,-2,1,4,-5,4})); //-> 6
+        System.out.println(maxSubArray(new int[]{1})); //-> 1
+        System.out.println(maxSubArray(new int[]{-2,-3,-1})); //-> -1
+    }
+}