Java HashTable Solution beats 99.77%

• ``````public class Solution {
public int maxSubArrayLen(int[] nums, int k) {
if(nums.length==0) return 0;
if(nums.length==1){
if(nums[0]==k) return 1;
return 0;
}
int[] sum = new int[nums.length+1];
sum[0] = 0;
for(int i=1;i<sum.length;i++){
sum[i] = sum[i-1] + nums[i-1];
}
Map<Integer, Integer> hashtable = new HashMap<Integer, Integer>();
for(int i=0;i<sum.length;i++){
hashtable.put(sum[i], i);
}
int max = 0;
for(int i=0;i<sum.length;i++){
Integer c = hashtable.get(sum[i]+k);
if(c != null && c.intValue() > i && c.intValue() - i > max)
max = c.intValue() - i;
}
return max;
}
}``````

• Can anybody explain me why this is much faster than

``````public class Solution {
public int maxSubArrayLen(int[] nums, int k) {
int sum = 0, max = 0;
HashMap<Integer, Integer> map = new HashMap<>();
for (int i = 0; i < nums.length; i++) {
sum = sum + nums[i];
if (sum == k) max = i + 1;
else if (map.containsKey(sum - k))
max = Math.max(max, i - map.get(sum - k));
if (!map.containsKey(sum)) map.put(sum, i);
}
return max;
}
}
``````

OP solution introduced more for 2 more for loops yet end up being faster. Both of the solution is O(n).

• @ratchapong.t Difference is constant. You have 2 if clause in loop, so it is 2n, which is larger than OP's. Since clauses like 'Integer c = hashtable.get(sum[i]+k);' does not take time.

• Why do you use

``````c.intValue()
``````

Instead of simply c since it is already an Integer the comparison should work.
I removed the .intValue() and the solution still works and it's actually faster.

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