Add 303_Range_Sum_Query_-_Immutable.java

Author: Sean Prashad

Dynamic Programming/303_Range_Sum_Query_-_Immutable.java

@@ -0,0 +1,24 @@
+class NumArray {
+    private int[] dp;
+
+    public NumArray(int[] nums) {
+        if (nums == null || nums.length == 0) {
+            return;
+        }
+
+        dp = new int[nums.length];
+        dp[0] = nums[0];
+
+        for (int i = 1; i < nums.length; i++) {
+            dp[i] = dp[i - 1] + nums[i];
+        }
+    }
+
+    public int sumRange(int i, int j) {
+        if (i == 0) {
+            return dp[j];
+        }
+
+        return dp[j] - dp[i - 1];
+    }
+}