Code reformat

Author: gouthampradhan

problems/src/array/BattleshipsInABoard.java

@@ -3,51 +3,52 @@
 /**
  * Created by gouthamvidyapradhan on 12/08/2017.
  * Given an 2D board, count how many battleships are in it. The battleships are represented with 'X's, empty slots are represented with '.'s. You may assume the following rules:
-
- You receive a valid board, made of only battleships or empty slots.
- Battleships can only be placed horizontally or vertically. In other words, they can only be made of the shape 1xN (1 row, N columns) or Nx1 (N rows, 1 column), where N can be of any size.
- At least one horizontal or vertical cell separates between two battleships - there are no adjacent battleships.
- Example:
- X..X
- ...X
- ...X
- In the above board there are 2 battleships.
- Invalid Example:
- ...X
- XXXX
- ...X
- This is an invalid board that you will not receive - as battleships will always have a cell separating between them.
-
- Follow up:
- Could you do it in one-pass, using only O(1) extra memory and without modifying the value of the board?
-
- Solution:
- The below solution works in one pass using only O(1) memory.
- Iterate through each cell and add one to count if and only if the current cell equals 'X' and its adjacent upper and
- left cell does not contain 'X'
+ * <p>
+ * You receive a valid board, made of only battleships or empty slots.
+ * Battleships can only be placed horizontally or vertically. In other words, they can only be made of the shape 1xN (1 row, N columns) or Nx1 (N rows, 1 column), where N can be of any size.
+ * At least one horizontal or vertical cell separates between two battleships - there are no adjacent battleships.
+ * Example:
+ * X..X
+ * ...X
+ * ...X
+ * In the above board there are 2 battleships.
+ * Invalid Example:
+ * ...X
+ * XXXX
+ * ...X
+ * This is an invalid board that you will not receive - as battleships will always have a cell separating between them.
+ * <p>
+ * Follow up:
+ * Could you do it in one-pass, using only O(1) extra memory and without modifying the value of the board?
+ * <p>
+ * Solution:
+ * The below solution works in one pass using only O(1) memory.
+ * Iterate through each cell and add one to count if and only if the current cell equals 'X' and its adjacent upper and
+ * left cell does not contain 'X'
  */
 public class BattleshipsInABoard {
     /**
      * Main method
+     *
      * @param args
      * @throws Exception
      */
-    public static void main(String[] args) throws Exception{
+    public static void main(String[] args) throws Exception {
         char[][] board = {{'X', '.', '.', 'X'}, {'.', '.', '.', 'X'}, {'.', '.', '.', 'X'}};
         System.out.println(new BattleshipsInABoard().countBattleships(board));
     }
 
     public int countBattleships(char[][] board) {
         int count = 0;
-        for(int i = 0; i < board.length; i ++){
-            for(int j = 0; j < board[0].length; j ++){
-                if(board[i][j] == 'X'){
-                    if(i - 1 >= 0){ //check for the boundary condition
-                        if(board[i - 1][j] == 'X')
+        for (int i = 0; i < board.length; i++) {
+            for (int j = 0; j < board[0].length; j++) {
+                if (board[i][j] == 'X') {
+                    if (i - 1 >= 0) { //check for the boundary condition
+                        if (board[i - 1][j] == 'X')
                             continue;
                     }
-                    if(j - 1 >= 0){
-                        if(board[i][j - 1] == 'X'){
+                    if (j - 1 >= 0) {
+                        if (board[i][j - 1] == 'X') {
                             continue;
                         }
                     }

problems/src/array/CanPlaceFlowers.java

@@ -3,48 +3,47 @@
 /**
  * Created by gouthamvidyapradhan on 10/06/2017.
  * Accepted
- *
- Suppose you have a long flowerbed in which some of the plots are planted and some are not. However, flowers cannot be planted in adjacent plots - they would compete for water and both would die.
-
- Given a flowerbed (represented as an array containing 0 and 1, where 0 means empty and 1 means not empty), and a number n, return if n new flowers can be planted in it without violating the no-adjacent-flowers rule.
-
- Example 1:
- Input: flowerbed = [1,0,0,0,1], n = 1
- Output: True
- Example 2:
- Input: flowerbed = [1,0,0,0,1], n = 2
- Output: False
- Note:
- The input array won't violate no-adjacent-flowers rule.
- The input array size is in the range of [1, 20000].
- n is a non-negative integer which won't exceed the input array size.
+ * <p>
+ * Suppose you have a long flowerbed in which some of the plots are planted and some are not. However, flowers cannot be planted in adjacent plots - they would compete for water and both would die.
+ * <p>
+ * Given a flowerbed (represented as an array containing 0 and 1, where 0 means empty and 1 means not empty), and a number n, return if n new flowers can be planted in it without violating the no-adjacent-flowers rule.
+ * <p>
+ * Example 1:
+ * Input: flowerbed = [1,0,0,0,1], n = 1
+ * Output: True
+ * Example 2:
+ * Input: flowerbed = [1,0,0,0,1], n = 2
+ * Output: False
+ * Note:
+ * The input array won't violate no-adjacent-flowers rule.
+ * The input array size is in the range of [1, 20000].
+ * n is a non-negative integer which won't exceed the input array size.
  */
-public class CanPlaceFlowers
-{
+public class CanPlaceFlowers {
     /**
      * Main method
+     *
      * @param args
      * @throws Exception
      */
-    public static void main(String[] args) throws Exception
-    {
-        int[] n = {1,0,0,0,1};
+    public static void main(String[] args) throws Exception {
+        int[] n = {1, 0, 0, 0, 1};
         System.out.println(new CanPlaceFlowers().canPlaceFlowers(n, 1));
     }
 
     public boolean canPlaceFlowers(int[] flowerbed, int n) {
 
         int[] T = new int[flowerbed.length + 4];
-        for(int i = 0, j = 2; i < flowerbed.length; i ++)
+        for (int i = 0, j = 2; i < flowerbed.length; i++)
             T[j++] = flowerbed[i];
         T[0] = 1;
         T[T.length - 1] = 1;
         int total = 0, count = 0;
-        for(int i = 1; i < T.length; i ++) {
-            if(T[i] == 0)
+        for (int i = 1; i < T.length; i++) {
+            if (T[i] == 0)
                 count++;
             else {
-                if((count % 2) == 0)
+                if ((count % 2) == 0)
                     total += ((count / 2) - 1);
                 else
                     total += (count / 2);

problems/src/array/FirstMissingPositive.java

@@ -3,40 +3,41 @@
 /**
  * Created by gouthamvidyapradhan on 24/06/2017.
  * Given an unsorted integer array, find the first missing positive integer.
-
- For example,
- Given [1,2,0] return 3,
- and [3,4,-1,1] return 2.
-
- Your algorithm should run in O(n) time and uses constant space.
+ * <p>
+ * For example,
+ * Given [1,2,0] return 3,
+ * and [3,4,-1,1] return 2.
+ * <p>
+ * Your algorithm should run in O(n) time and uses constant space.
  */
 public class FirstMissingPositive {
     private int L;
-    public static void main(String[] args) throws Exception{
+
+    public static void main(String[] args) throws Exception {
         int[] nums = {1, 3, 5, 9};
         System.out.println(new FirstMissingPositive().firstMissingPositive(nums));
     }
 
     public int firstMissingPositive(int[] nums) {
         L = nums.length;
-        for(int i = 0; i < L; i ++){
-            if(nums[i] > 0 && nums[i] <= L && nums[i] != i + 1){
+        for (int i = 0; i < L; i++) {
+            if (nums[i] > 0 && nums[i] <= L && nums[i] != i + 1) {
                 int v = nums[i];
                 nums[i] = -1;
                 replace(v, nums);
             }
         }
 
-        for(int i = 0; i < L; i ++){
-            if(nums[i] != i + 1)
+        for (int i = 0; i < L; i++) {
+            if (nums[i] != i + 1)
                 return i + 1;
         }
 
         return L + 1;
     }
 
-    private void replace(int i, int[] nums){
-        if(i > 0 && i <= L && i != nums[i - 1]){
+    private void replace(int i, int[] nums) {
+        if (i > 0 && i <= L && i != nums[i - 1]) {
             int v = nums[i - 1];
             nums[i - 1] = i;
             replace(v, nums);

problems/src/array/MaxProductOfThreeNumbers.java

@@ -5,20 +5,20 @@
 /**
  * Created by gouthamvidyapradhan on 27/06/2017.
  * Given an integer array, find three numbers whose product is maximum and output the maximum product.
-
- Example 1:
- Input: [1,2,3]
- Output: 6
- Example 2:
- Input: [1,2,3,4]
- Output: 24
- Note:
- The length of the given array will be in range [3,104] and all elements are in the range [-1000, 1000].
- Multiplication of any three numbers in the input won't exceed the range of 32-bit signed integer.
+ * <p>
+ * Example 1:
+ * Input: [1,2,3]
+ * Output: 6
+ * Example 2:
+ * Input: [1,2,3,4]
+ * Output: 24
+ * Note:
+ * The length of the given array will be in range [3,104] and all elements are in the range [-1000, 1000].
+ * Multiplication of any three numbers in the input won't exceed the range of 32-bit signed integer.
  */
 public class MaxProductOfThreeNumbers {
     public static void main(String[] args) {
-        int[] A = {1,2,3};
+        int[] A = {1, 2, 3};
         System.out.println(new MaxProductOfThreeNumbers().maximumProduct(A));
     }
 

problems/src/array/MergeIntervals.java

@@ -1,33 +1,41 @@
 package array;
 
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
 
 /**
  * Created by gouthamvidyapradhan on 13/06/2017.
  * Given a collection of intervals, merge all overlapping intervals.
-
- For example,
- Given [1,3],[2,6],[8,10],[15,18],
- return [1,6],[8,10],[15,18].
-
- Solution: O(N log N) where N is the number of intervals
- 1. Sort the intervals based on start index
- 2. Mark the first interval as the current interval
- 3. For every ith interval starting 1 -> N, if the ith interval overlaps with the current interval then create a new
- current interval. Else, add the current interval to result set and begin a new current interval.
-
+ * <p>
+ * For example,
+ * Given [1,3],[2,6],[8,10],[15,18],
+ * return [1,6],[8,10],[15,18].
+ * <p>
+ * Solution: O(N log N) where N is the number of intervals
+ * 1. Sort the intervals based on start index
+ * 2. Mark the first interval as the current interval
+ * 3. For every ith interval starting 1 -> N, if the ith interval overlaps with the current interval then create a new
+ * current interval. Else, add the current interval to result set and begin a new current interval.
  */
-public class MergeIntervals
-{
+public class MergeIntervals {
     public static class Interval {
         int start;
         int end;
-        Interval() { start = 0; end = 0; }
-        Interval(int s, int e) { start = s; end = e; }
+
+        Interval() {
+            start = 0;
+            end = 0;
+        }
+
+        Interval(int s, int e) {
+            start = s;
+            end = e;
+        }
     }
 
-    public static void main(String[] args) throws Exception
-    {
+    public static void main(String[] args) throws Exception {
         Interval i1 = new Interval(1, 2);
         Interval i2 = new Interval(3, 4);
         Interval i3 = new Interval(5, 6);
@@ -37,16 +45,15 @@ public static void main(String[] args) throws Exception
     }
 
     public List<Interval> merge(List<Interval> intervals) {
-        if(intervals.isEmpty()) return new ArrayList<>();
+        if (intervals.isEmpty()) return new ArrayList<>();
         Collections.sort(intervals, (o1, o2) -> Integer.compare(o1.start, o2.start));
         List<Interval> result = new ArrayList<>();
         Interval curr = intervals.get(0);
-        for(int i = 1, l = intervals.size(); i < l; i ++) {
+        for (int i = 1, l = intervals.size(); i < l; i++) {
             Interval I = intervals.get(i);
-            if(I.start >= curr.start && I.start <= curr.end) { //check if the new interval overlaps with the current
+            if (I.start >= curr.start && I.start <= curr.end) { //check if the new interval overlaps with the current
                 curr.end = curr.end > I.end ? curr.end : I.end;
-            }
-            else {
+            } else {
                 result.add(curr);
                 curr = I;
             }

problems/src/array/MergeSortedArray.java

@@ -3,24 +3,24 @@
 /**
  * Created by gouthamvidyapradhan on 29/07/2017.
  * Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array.
-
- Note:
- You may assume that nums1 has enough space (size that is greater or equal to m + n) to hold additional elements from nums2. The number of elements initialized in nums1 and nums2 are m and n respectively.
+ * <p>
+ * Note:
+ * You may assume that nums1 has enough space (size that is greater or equal to m + n) to hold additional elements from nums2. The number of elements initialized in nums1 and nums2 are m and n respectively.
  */
 public class MergeSortedArray {
-    public static void main(String[] args) throws Exception{
+    public static void main(String[] args) throws Exception {
         int[] A = {0};
         int[] B = {1};
         new MergeSortedArray().merge(A, 0, B, 1);
-        for(int i : A)
+        for (int i : A)
             System.out.println(i);
     }
 
     public void merge(int[] nums1, int m, int[] nums2, int n) {
         int i = m + n - 1, j = m - 1, k = n - 1;
-        while(j >= 0 && k >= 0)
+        while (j >= 0 && k >= 0)
             nums1[i--] = (nums1[j] > nums2[k]) ? nums1[j--] : nums2[k--];
-        while(k >= 0)
+        while (k >= 0)
             nums1[i--] = nums2[k--];
     }
 

problems/src/array/MissingNumber.java

@@ -3,27 +3,28 @@
 /**
  * Created by gouthamvidyapradhan on 04/07/2017.
  * Given an array containing n distinct numbers taken from 0, 1, 2, ..., n, find the one that is missing from the array.
-
- For example,
- Given nums = [0, 1, 3] return 2.
-
- Note:
- Your algorithm should run in linear runtime complexity. Could you implement it using only constant extra space complexity?
+ * <p>
+ * For example,
+ * Given nums = [0, 1, 3] return 2.
+ * <p>
+ * Note:
+ * Your algorithm should run in linear runtime complexity. Could you implement it using only constant extra space complexity?
  */
 public class MissingNumber {
 
-    public static void main(String[] args) throws Exception{
+    public static void main(String[] args) throws Exception {
         int[] nums = {0};
         System.out.println(new MissingNumber().missingNumber(nums));
     }
-    public int missingNumber(int[] nums){
+
+    public int missingNumber(int[] nums) {
         int sum = 0;
         int n = nums.length;
         for (int num : nums) {
             sum += num;
         }
         int arrSum = (((n + 1)) * n) / 2;
-        if(arrSum == sum) return 0;
+        if (arrSum == sum) return 0;
         else return arrSum - sum;
     }
 }