Merge pull request #108 from Shubh-k04/patch-2

 Adding interview Question "Number of Subarray"

Java/Algorithm/NumberOfSubarray.java

@@ -0,0 +1,23 @@
+/*
+Given an array of integers nums and an integer k, return the total number of continuous subarrays whose sum equals to k.
+*/
+import java.util.HashMap;
+import java.util.Map;
+
+public class NumberOfSubarray {
+	public int subarraySum(int[] nums, int k)
+	{
+		 int curr_sum = 0;
+	        int cnt = 0;
+	        Map<Integer, Integer> map = new HashMap<>();
+	        map.put(0, 1);
+	        for(int i=0;i<nums.length;i++){
+	            curr_sum += nums[i];
+	            if(map.containsKey(curr_sum - k)){
+	                cnt += map.get(curr_sum - k);
+	            }
+	            map.put(curr_sum, map.getOrDefault(curr_sum, 0) + 1);
+	        }
+	        return cnt;
+    }
+}