1.Two Sum

Topics

Given an array of integers, find the numbers such that they add up to a specific target number.

The function twosum should return indices of the numbers such that they add up to the target, where index1 must is Les S than Index2. Please note that your returned answers (both Index1 and INDEX2) is not zero-based.

You may assume this each input would has exactly one solution.

Input: numbers={2, 7, one, target=9
Output: index1=1, index2=2

Thinking of solving problems

Use brute force solution. Time Complexity O (n^2), spatial complexity O (1).

Use the hash table to store the number of accesses. Time complexity O (n), spatial complexity O (n). √

Code

Int[] Twosum (int[] nums, int target) {Hashmap<integer, integer> HM = new Hashmap<integer, integer> (); int[] Ind Ex=new int[2];for (int i=0;; i++) {if (Hm.containskey (Target-nums[i])) {index[0] = Hm.get (Target-nums[i]) +1;index[1] = I+1;break;} Else{hm.put (Nums[i],i);}} return index;}

Run results

Submit Time	Status	Run Time	Language
Minutes ago	Accepted	380 ms	Java

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1.Two Sum