Init commit

Author: joshguha

.gitignore

@@ -0,0 +1,13 @@
+2-addTwoNumbers.js
+3-lengthOfLongestSubstring.js
+4-medianOfTwoSortedArrays.js
+5-longestPalindromicSubstring.js
+6-ZigZagConversion.js
+7-reverseInteger.js
+8-stringToInteger(atoi).js
+9-palindromeNumber.js
+11-containerWithMostWater.js
+12-integerToRoman.js
+13-romanToInteger.js
+14-longestCommonPrefix.js
+15-threeSum.js

1-twoSum.js

@@ -0,0 +1,79 @@
+// var twoSum = function (nums, target) {
+//     for (let i = 0; i < nums.length; i++) {
+//         for (let j = 0; j < nums.length; j++) {
+//             let num1 = nums[i];
+//             let num2 = nums[j];
+//             if (num1 !== num2) {
+//                 let sum = num1 + num2;
+//                 if (sum === target) {
+//                     return [i, j];
+//                 }
+//             }
+//         }
+//     }
+// };
+
+// Faster Algorithm (O(n))
+
+let twoSum = function (nums, target) {
+    let mergeSort = function (array) {
+        let merge = function (firstArray, secondArray) {
+            let i = 0;
+            let j = 0;
+            let result = [];
+            while (true) {
+                if (firstArray[i] < secondArray[j]) {
+                    result.push(firstArray[i]);
+                    i++;
+                } else {
+                    result.push(secondArray[j]);
+                    j++;
+                }
+
+                if (i === firstArray.length) {
+                    return result.concat(
+                        secondArray.slice(j, secondArray.length)
+                    );
+                } else if (j === secondArray.length) {
+                    return result.concat(
+                        firstArray.slice(i, firstArray.length)
+                    );
+                }
+            }
+        };
+
+        if (array.length === 1) {
+            return array;
+        }
+        const middleIndex = Math.floor(array.length / 2);
+        const firstArray = mergeSort(array.slice(0, middleIndex));
+        const secondArray = mergeSort(array.slice(middleIndex, array.length));
+        const merged = merge(firstArray, secondArray);
+        return merged;
+    };
+
+    sortedArray = mergeSort(nums);
+    let i = 0;
+    let j = sortedArray.length - 1;
+
+    while (true) {
+        let sum = sortedArray[i] + sortedArray[j];
+        if (sum > target) {
+            j--;
+        } else if (sum < target) {
+            i++;
+        } else {
+            let index1 = nums.indexOf(sortedArray[i]);
+            nums[index1] = undefined;
+            let index2 = nums.indexOf(sortedArray[j]);
+
+            return [index1, index2];
+        }
+
+        if (i > j) {
+            return "No solution";
+        }
+    }
+};
+
+console.log(twoSum([3, 2, 4], 6));