Adding Stack & Strings | Formatting

Author: Prashant Jain

src/in/knowledgegate/dsa/array/MaximumSubArray.java

@@ -1,26 +1,19 @@
 package in.knowledgegate.dsa.array;
 
 /**
- * Given an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return its sum.
- * A subarray is a contiguous part of an array.
- *
- * Example 1
- * Input: nums = [-2,1,-3,4,-1,2,1,-5,4]
- * Output: 6
- * Explanation: [4,-1,2,1] has the largest sum = 6.
- *
- * Example 2:
- * Input: nums = [1]
- * Output: 1
- *
- * Example 3:
- * Input: nums = [5,4,-1,7,8]
- * Output: 23
- *
- *
- * Constraints:
- * 1 <= nums.length <= 105
- * -104 <= nums[i] <= 104
+ * Given an integer array nums, find the contiguous subarray (containing at
+ * least one number) which has the largest sum and return its sum. A subarray is
+ * a contiguous part of an array.
+ * <p>
+ * Example 1 Input: nums = [-2,1,-3,4,-1,2,1,-5,4] Output: 6 Explanation:
+ * [4,-1,2,1] has the largest sum = 6.
+ * <p>
+ * Example 2: Input: nums = [1] Output: 1
+ * <p>
+ * Example 3: Input: nums = [5,4,-1,7,8] Output: 23
+ * <p>
+ * <p>
+ * Constraints: 1 <= nums.length <= 105 -104 <= nums[i] <= 104
  */
 public class MaximumSubArray {
     public int maxSubArray(int[] nums) {

src/in/knowledgegate/dsa/array/RemoveDuplicatesSortedArray.java

@@ -1,29 +1,33 @@
 package in.knowledgegate.dsa.array;
 
 /**
- * Given an integer array nums sorted in non-decreasing order, remove the duplicates in-place such that each unique element appears only once. The relative order of the elements should be kept the same.
- * Since it is impossible to change the length of the array in some languages, you must instead have the result be placed in the first part of the array nums. More formally, if there are k elements after removing the duplicates, then the first k elements of nums should hold the final result. It does not matter what you leave beyond the first k elements.
- * Return k after placing the final result in the first k slots of nums.
- *
- * Do not allocate extra space for another array. You must do this by modifying the input array in-place with O(1) extra memory.
- *
- * Example 1:
- * Input: nums = [1,1,2]
- * Output: 2, nums = [1,2,_]
- * Explanation: Your function should return k = 2, with the first two elements of nums being 1 and 2 respectively.
- * It does not matter what you leave beyond the returned k (hence they are underscores).
- *
- *  Example 2:
- * Input: nums = [0,0,1,1,1,2,2,3,3,4]
- * Output: 5, nums = [0,1,2,3,4,_,_,_,_,_]
- * Explanation: Your function should return k = 5, with the first five elements of nums being 0, 1, 2, 3, and 4 respectively.
- * It does not matter what you leave beyond the returned k (hence they are underscores).
- *
- *
- * Constraints:
- * 1 <= nums.length <= 3 * 104
- * -100 <= nums[i] <= 100
- * nums is sorted in non-decreasing order.
+ * Given an integer array nums sorted in non-decreasing order, remove the
+ * duplicates in-place such that each unique element appears only once. The
+ * relative order of the elements should be kept the same. Since it is
+ * impossible to change the length of the array in some languages, you must
+ * instead have the result be placed in the first part of the array nums. More
+ * formally, if there are k elements after removing the duplicates, then the
+ * first k elements of nums should hold the final result. It does not matter
+ * what you leave beyond the first k elements. Return k after placing the final
+ * result in the first k slots of nums.
+ * <p>
+ * Do not allocate extra space for another array. You must do this by modifying
+ * the input array in-place with O(1) extra memory.
+ * <p>
+ * Example 1: Input: nums = [1,1,2] Output: 2, nums = [1,2,_] Explanation: Your
+ * function should return k = 2, with the first two elements of nums being 1 and
+ * 2 respectively. It does not matter what you leave beyond the returned k
+ * (hence they are underscores).
+ * <p>
+ * Example 2: Input: nums = [0,0,1,1,1,2,2,3,3,4] Output: 5, nums =
+ * [0,1,2,3,4,_,_,_,_,_] Explanation: Your function should return k = 5, with
+ * the first five elements of nums being 0, 1, 2, 3, and 4 respectively. It does
+ * not matter what you leave beyond the returned k (hence they are
+ * underscores).
+ * <p>
+ * <p>
+ * Constraints: 1 <= nums.length <= 3 * 104 -100 <= nums[i] <= 100 nums is
+ * sorted in non-decreasing order.
  */
 public class RemoveDuplicatesSortedArray {
     public int removeDuplicates(int[] nums) {

src/in/knowledgegate/dsa/array/SearchInsertPosition.java

@@ -1,28 +1,21 @@
 package in.knowledgegate.dsa.array;
 
 /**
- * Given a sorted array of distinct integers and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.
- * You must write an algorithm with O(log n) runtime complexity.
- *
- *
- * Example 1:
- * Input: nums = [1,3,5,6], target = 5
- * Output: 2
- *
- * Example 2:
- * Input: nums = [1,3,5,6], target = 2
- * Output: 1
- *
- * Example 3:
- * Input: nums = [1,3,5,6], target = 7
- * Output: 4
- *
- *
- * Constraints:
- * 1 <= nums.length <= 104
- * -104 <= nums[i] <= 104
- * nums contains distinct values sorted in ascending order.
- * -104 <= target <= 104
+ * Given a sorted array of distinct integers and a target value, return the
+ * index if the target is found. If not, return the index where it would be if
+ * it were inserted in order. You must write an algorithm with O(log n) runtime
+ * complexity.
+ * <p>
+ * <p>
+ * Example 1: Input: nums = [1,3,5,6], target = 5 Output: 2
+ * <p>
+ * Example 2: Input: nums = [1,3,5,6], target = 2 Output: 1
+ * <p>
+ * Example 3: Input: nums = [1,3,5,6], target = 7 Output: 4
+ * <p>
+ * <p>
+ * Constraints: 1 <= nums.length <= 104 -104 <= nums[i] <= 104 nums contains
+ * distinct values sorted in ascending order. -104 <= target <= 104
  */
 public class SearchInsertPosition {
     public int searchInsert(int[] nums, int target) {
@@ -31,7 +24,7 @@ public int searchInsert(int[] nums, int target) {
             int mid = beg + (end - beg) / 2;
             if (nums[mid] == target) {
                 return mid;
-            } else if(nums[mid] > target) {
+            } else if (nums[mid] > target) {
                 end = mid - 1;
             } else {
                 beg = mid + 1;

src/in/knowledgegate/dsa/array/TwoSum.java

@@ -4,29 +4,21 @@
 import java.util.Map;
 
 /**
- * Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.
- * You may assume that each input would have exactly one solution, and you may not use the same element twice.
+ * Given an array of integers nums and an integer target, return indices of the
+ * two numbers such that they add up to target. You may assume that each input
+ * would have exactly one solution, and you may not use the same element twice.
  * You can return the answer in any order.
- *
- * Example 1:
- * Input: nums = [2,7,11,15], target = 9
- * Output: [0,1]
- * Explanation: Because nums[0] + nums[1] == 9, we return [0, 1].
- *
- * Example 2:
- * Input: nums = [3,2,4], target = 6
- * Output: [1,2]
- *
- * Example 3:
- * Input: nums = [3,3], target = 6
- * Output: [0,1]
- *
- *
- * Constraints:
- * 2 <= nums.length <= 104
- * -109 <= nums[i] <= 109
- * -109 <= target <= 109
- * Only one valid answer exists.
+ * <p>
+ * Example 1: Input: nums = [2,7,11,15], target = 9 Output: [0,1] Explanation:
+ * Because nums[0] + nums[1] == 9, we return [0, 1].
+ * <p>
+ * Example 2: Input: nums = [3,2,4], target = 6 Output: [1,2]
+ * <p>
+ * Example 3: Input: nums = [3,3], target = 6 Output: [0,1]
+ * <p>
+ * <p>
+ * Constraints: 2 <= nums.length <= 104 -109 <= nums[i] <= 109 -109 <= target <=
+ * 109 Only one valid answer exists.
  */
 public class TwoSum {
     public int[] twoSum(int[] nums, int target) {

src/in/knowledgegate/dsa/complexity/ArrayCopy.java

@@ -3,11 +3,11 @@
 public class ArrayCopy {
 
     public static void main(String[] args) {
-        int[] newCopy = copy(new int[]{1, 2, 3 , 4, 5});
+        int[] newCopy = copy(new int[]{1, 2, 3, 4, 5});
     }
 
-    private static int[] copy (int []array) {
-        int newCopy[] = new int[array.length];
+    private static int[] copy(int[] array) {
+        int[] newCopy = new int[array.length];
         for (int i = 0; i < array.length; i++) {
             newCopy[i] = array[i];
         }

src/in/knowledgegate/dsa/complexity/ArraySum.java

@@ -6,7 +6,7 @@ public static void main(String[] args) {
         System.out.println("Sum:" + sum(new int[]{1, 2, 3, 4, 5}));
     }
 
-    private static int sum (int []array) {
+    private static int sum(int[] array) {
         int result = 0;
         for (int i = 0; i < array.length; i++) {
             result += array[i];

src/in/knowledgegate/dsa/complexity/Sum.java

@@ -6,7 +6,7 @@ public static void main(String[] args) {
         System.out.println("Sum:" + sum(8, 10));
     }
 
-    private static int sum (int a, int b) {
+    private static int sum(int a, int b) {
         return a + b;
     }
 }

src/in/knowledgegate/dsa/linkedlist/PascalTriangle.java

@@ -4,20 +4,17 @@
 import java.util.List;
 
 /**
- * Given an integer numRows, return the first numRows of Pascal's triangle.
- * In Pascal's triangle, each number is the sum of the two numbers directly above it as shown.
- *
- * Example 1:
- * Input: numRows = 5
- * Output: [[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1]]
- *
- * Example 2:
- * Input: numRows = 1
- * Output: [[1]]
- *
- *
- * Constraints:
- * 1 <= numRows <= 30
+ * Given an integer numRows, return the first numRows of Pascal's triangle. In
+ * Pascal's triangle, each number is the sum of the two numbers directly above
+ * it as shown.
+ * <p>
+ * Example 1: Input: numRows = 5 Output:
+ * [[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1]]
+ * <p>
+ * Example 2: Input: numRows = 1 Output: [[1]]
+ * <p>
+ * <p>
+ * Constraints: 1 <= numRows <= 30
  */
 public class PascalTriangle {
     public List<List<Integer>> generate(int numRows) {

src/in/knowledgegate/dsa/stack/ValidParenthesis.java

@@ -0,0 +1,51 @@
+package in.knowledgegate.dsa.stack;
+
+import java.util.Stack;
+
+/**
+ * Given a string s containing just the characters '(', ')', '{', '}', '[' and
+ * ']', determine if the input string is valid. An input string is valid if:
+ * <p>
+ * Open brackets must be closed by the same type of brackets. Open brackets must
+ * be closed in the correct order.
+ * <p>
+ * <p>
+ * Example 1: Input: s = "()" Output: true
+ * <p>
+ * Example 2: Input: s = "()[]{}" Output: true
+ * <p>
+ * Example 3: Input: s = "(]" Output: false
+ * <p>
+ * Constraints: 1 <= s.length <= 104 s consists of parentheses only '()[]{}'.
+ */
+public class ValidParenthesis {
+    public boolean isValid(String s) {
+        Stack<Character> stack = new Stack<>();
+        for (int i = 0; i < s.length(); i++) {
+            char c = s.charAt(i);
+            switch (c) {
+                case '{':
+                case '[':
+                case '(':
+                    stack.push(c);
+                    break;
+                case '}':
+                    if (stack.isEmpty() || '{' != stack.pop()) {
+                        return false;
+                    }
+                    break;
+                case ']':
+                    if (stack.isEmpty() || '[' != stack.pop()) {
+                        return false;
+                    }
+                    break;
+                case ')':
+                    if (stack.isEmpty() || '(' != stack.pop()) {
+                        return false;
+                    }
+                    break;
+            }
+        }
+        return stack.isEmpty();
+    }
+}

src/in/knowledgegate/dsa/strings/LongestCommonPrefix.java

@@ -0,0 +1,29 @@
+package in.knowledgegate.dsa.strings;
+
+/**
+ * Write a function to find the longest common prefix string amongst an array of
+ * strings. If there is no common prefix, return an empty string "".
+ * <p>
+ * Example 1: Input: strs = ["flower","flow","flight"] Output: "fl"
+ * <p>
+ * Example 2: Input: strs = ["dog","racecar","car"] Output: "" Explanation:
+ * There is no common prefix among the input strings.
+ * <p>
+ * <p>
+ * Constraints: 1 <= strs.length <= 200 0 <= strs[i].length <= 200 strs[i]
+ * consists of only lower-case English letters.
+ */
+public class LongestCommonPrefix {
+    public String longestCommonPrefix(String[] strs) {
+        String result = "";
+        for (int i = 0; i < strs[0].length(); i++) {
+            for (int j = 1; j < strs.length; j++) {
+                if (strs[j].length() <= i || strs[0].charAt(i) != strs[j].charAt(i)) {
+                    return result;
+                }
+            }
+            result += strs[0].charAt(i);
+        }
+        return result;
+    }
+}