Merge branch 'master' into add/next_permutation

Author: ongzx

LeetcodeProblems/Algorithms/2Sum.js

@@ -0,0 +1,43 @@
+/**
+2 Sum
+https://leetcode.com/problems/two-sum/
+
+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]
+
+*/
+
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number[]}
+ */
+ var twoSum = function(nums, target) {
+  let map ={};
+  for(let i=0;i<nums.length;i++){
+      const sum = target-nums[i];
+      if(map[parseInt(sum)] != 0){
+          return [map[sum], i];
+      } else{
+          map[nums[i]] = i;
+      }
+  }
+};
+
+module.exports.twoSum = twoSum;

LeetcodeProblems/Algorithms/Longest_Common_Prefix.js

@@ -0,0 +1,34 @@
+/**
+Longest Common Prefix
+https://leetcode.com/problems/longest-common-prefix/
+
+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 "".
+
+Example 1:
+Input: strs = ["flower","flow","flight"]
+Output: "fl"
+
+Example 2:
+Input: strs = ["dog","racecar","car"]
+Output: ""
+Explanation: There is no common prefix among the input strings.
+
+*/
+
+/**
+ * @param {string[]} strs
+ * @return {string}
+ */
+ var longestCommonPrefix = function(strs) {
+  if(strs.length === 0) return "";
+  
+  return strs.reduce((result, curr)=>{
+      let i = 0;
+      while(result[i] && curr[i] && result[i] === curr[i]) i++;
+      return result.slice(0, i);
+  });
+};
+
+module.exports.longestCommonPrefix = longestCommonPrefix;

LeetcodeProblems/Algorithms/Reverse_Integer.js

@@ -0,0 +1,46 @@
+/**
+Reverse Integer
+https://leetcode.com/problems/reverse-integer/
+
+Given a signed 32-bit integer x, return x with its digits reversed. If reversing x causes the value to go outside the signed 32-bit integer range [-231, 231 - 1], then return 0.
+
+Assume the environment does not allow you to store 64-bit integers (signed or unsigned).
+
+Example 1:
+Input: x = 123
+Output: 321
+
+Example 2:
+Input: x = -123
+Output: -321
+
+Example 3:
+Input: x = 120
+Output: 21
+
+ */
+
+/**
+ * @param {number} x
+ * @return {number}
+ */
+var reverseInteger = function(x) {
+  const sign = x >= 0 ? 1 : -1;
+  
+  let baseNum = sign * x;
+  let builder = 0;
+  
+  while (baseNum > 0) {
+    const digit = baseNum % 10;
+    builder = builder * 10 + digit;
+    baseNum = (baseNum / 10) | 0;
+  }
+  
+  builder *= sign;
+  
+  const isWithinRange = (builder >= -Math.pow(2, 31) && builder <= Math.pow(2, 31) - 1);
+  
+  return isWithinRange ? builder : 0;
+};
+
+module.exports.reverseInteger = reverseInteger;

LeetcodeProblemsTests/Algorithms/2Sum_Test.js

@@ -0,0 +1,11 @@
+const assert = require('assert');
+const twoSum = require('../../LeetcodeProblems/Algorithms/2Sum').twoSum;
+
+var test = function () {
+  assert.deepEqual([0,1], twoSum([2,7,11,15], 9));
+  assert.deepEqual([1,2], twoSum([3,2,4], 6));
+  assert.deepEqual([0,1], twoSum([3,3], 6));
+}
+
+module.exports.test = test;
+

LeetcodeProblemsTests/Algorithms/Longest_Common_Prefix_Test.js

@@ -0,0 +1,11 @@
+
+const assert = require('assert');
+const longestCommonPrefix = require('../../LeetcodeProblems/Algorithms/Longest_Common_Prefix').longestCommonPrefix;
+
+function test() {
+  assert.equal(longestCommonPrefix(["flower","flow","flight"]), "fl");
+  assert.equal(longestCommonPrefix(["dog","racecar","car"]), "");
+  assert.equal(longestCommonPrefix([]), "");
+}
+
+module.exports.test = test;

LeetcodeProblemsTests/Algorithms/Reverse_Integer_Test.js

@@ -0,0 +1,11 @@
+const assert = require('assert');
+const reverseInteger = require('../../LeetcodeProblems/Algorithms/Reverse_Integer').reverseInteger;
+
+var test = function() {
+  assert.equal(reverseInteger(123), 321);
+  assert.equal(reverseInteger(-123), -321);
+  assert.equal(reverseInteger(120), 21);
+}
+
+
+module.exports.test = test;

README.md

@@ -64,7 +64,8 @@ To run a specific problem in your console run  `node <problem_file_path>` (e.g.
 | [Maximum Sum of an Hourglass](/LeetcodeProblems/Algorithms/Maximise_Hour_Glass_Sum.js)                          | Medium | https://leetcode.com/problems/maximum-sum-of-an-hourglass/ |
 | [Next Permutation](/LeetcodeProblems/Algorithms/Next_Permutation.js)                                            | Medium | https://leetcode.com/problems/next-permutation/ |
 | [Time Needed to Rearrange a Binary String](/LeetcodeProblems/Algorithms/Time_Needed_Rearrange_Binary_String.js)| Medium | https://leetcode.com/problems/time-needed-to-rearrange-a-binary-string/ |
-| [Find Subarrays With Equal Sum ](/LeetcodeProblems/Algorithms/Find_Subarrays_With_Equal_Sums.js)                                                                   | Medium | https://leetcode.com/problems/find-subarrays-with-equal-sum/ | 
+| [Find Subarrays With Equal Sum ](/LeetcodeProblems/Algorithms/Find_Subarrays_With_Equal_Sums.js)                | Medium | https://leetcode.com/problems/find-subarrays-with-equal-sum/ | 
+| [Reverse Integer](/LeetcodeProblems/Algorithms/Reverse_Integer.js)                                              | Medium | https://leetcode.com/problems/reverse-integer/ |
 | [Flood Fill ](/LeetcodeProblems/Algorithms/Flood_Fill.js)                                                       | Easy   | https://leetcode.com/problems/flood-fill/ |
 | [Implement stack using queues ](/LeetcodeProblems/Algorithms/Implement_stack_using_queues.js)                   | Easy   | https://leetcode.com/problems/implement-stack-using-queues/ |
 | [Number of Segments in a String ](/LeetcodeProblems/Algorithms/Number_of_Segments_in_a_String.js)               | Easy   | https://leetcode.com/problems/number-of-segments-in-a-string/ |
@@ -79,6 +80,8 @@ To run a specific problem in your console run  `node <problem_file_path>` (e.g.
 | [Binary Gap ](/LeetcodeProblems/Algorithms/Binary_Gap.js)                                                       | Easy   | https://leetcode.com/problems/binary-gap/ |
 | [Binary Gap ](/LeetcodeProblems/Algorithms/Binary_Gap.js)                                                       | Easy   | https://leetcode.com/problems/binary-gap/ |
 | [Majority Element](/LeetcodeProblems/Algorithms/Majority_Element.js)                                            | Easy   | https://leetcode.com/problems/majority-element/ |
+| [Longest Common Prefix](/LeetcodeProblems/Algorithms/Longest_Common_Prefix.js)                                  | Easy   | https://leetcode.com/problems/longest-common-prefix/ |
+| [Two Sum](/LeetcodeProblems/Algorithms/2Sum.js)                                                                 | Easy   | https://leetcode.com/problems/two-sum/ |
 | [Tic Tac Toe ](/LeetcodeProblems/Algorithms/Tic_Tac_Toe.js)                                                     |        | |
 | [Permutations With Duplicates ](/LeetcodeProblems/Algorithms/Permutations_With_Duplicates.js)                   |        | |
 | [Deletion Distance](/LeetcodeProblems/Algorithms/Deletion_Distance.js)                                          |        | |