Leetcode-maximum Size subarray Sum Equals k

Given an array nums and a target value K, find the maximum length of a subarray that sums to K. If there isn ' t one, return 0 instead.

Example 1:

Given nums = [1, -1, 5, -2, 3] , k = 3 ,
Return 4 . (Because the Subarray sums to 3 and is the [1, -1, 5, -2] longest)

Example 2:

Given nums = [-2, -1, 2, 1] , k = 1 ,
Return 2 . (Because the Subarray sums to 1 and is the [-1, 2] longest)

Follow up:
Can do it in O (n) time?

Analysis:use a HashMap to store pair of <sum Val, Ind&gt, and then for each sum[i], we query whether there is <sum[i]-  K, X>, if yes, then we found one candidate. Solution:

1  Public classSolution {2      Public intMaxsubarraylen (int[] Nums,intk) {3         intres = 0, Len =nums.length;4Map<integer,integer> Summap =NewHashmap<integer,integer>(); 5 6         intSum=0;7          for(inti=0;i<len;i++){8Sum + =Nums[i];9             if(sum==k) {Tenres = i+1; One}Else if(Summap.containskey (sum-k)) { Ares = Math.max (res, i-summap.get (sum-k)); -             } -             if(!summap.containskey (sum)) { the Summap.put (sum,i); -             }     -         } -  +         returnRes; -     } +}

Leetcode-maximum Size subarray Sum Equals k