solve problem Range Sum Query Immutable

Author: P-ppc

README.md

@@ -57,6 +57,7 @@ All solutions will be accepted!
 |811|[Subdomain Visit Count](https://leetcode-cn.com/problems/subdomain-visit-count/description/)|[java/py/js](./algorithms/SubdomainVisitCount)|Easy|
 |637|[Average Of Levels In Binary Tree](https://leetcode-cn.com/problems/average-of-levels-in-binary-tree/description/)|[java/py/js](./algorithms/AverageOfLevelsInBinaryTree)|Easy|
 |118|[Pascals Triangle](https://leetcode-cn.com/problems/pascals-triangle/description/)|[java/py/js](./algorithms/PascalsTriangle)|Easy|
+|303|[Range Sum Query Immutable](https://leetcode-cn.com/problems/range-sum-query-immutable/description/)|[java/py/js](./algorithms/RangeSumQueryImmutable)|Easy|
 
 # Database
 |#|Title|Solution|Difficulty|

algorithms/RangeSumQueryImmutable/README.md

@@ -0,0 +1,2 @@
+# Range Sum Query Immutable
+Use advance calculation to solve this problem

algorithms/RangeSumQueryImmutable/Solution.java

@@ -0,0 +1,19 @@
+class NumArray {
+    Map<Integer, Integer> sumMap = new HashMap<Integer, Integer>();
+    
+    public NumArray(int[] nums) {
+        for (int i = 0; i < nums.length; i++) {
+            sumMap.put(i, i == 0 ? nums[i] : sumMap.get(i - 1) + nums[i]);
+        }    
+    }
+    
+    public int sumRange(int i, int j) {
+        return i == 0 ? sumMap.get(j) : sumMap.get(j) - sumMap.get(i - 1);
+    }
+}
+
+/**
+ * Your NumArray object will be instantiated and called as such:
+ * NumArray obj = new NumArray(nums);
+ * int param_1 = obj.sumRange(i,j);
+ */

algorithms/RangeSumQueryImmutable/solution.js

@@ -0,0 +1,32 @@
+/**
+ * @param {number[]} nums
+ */
+var NumArray = function(nums) {
+    this.sumMap = {}
+    nums.forEach((num, index) => {
+        if (index === 0) {
+            this.sumMap[index] = num
+        } else {
+            this.sumMap[index] = this.sumMap[index - 1] + num
+        }
+    })
+};
+
+/** 
+ * @param {number} i 
+ * @param {number} j
+ * @return {number}
+ */
+NumArray.prototype.sumRange = function(i, j) {
+    if (i === 0) {
+        return this.sumMap[j]
+    } else {
+        return this.sumMap[j] - this.sumMap[i - 1]
+    }
+};
+
+/** 
+ * Your NumArray object will be instantiated and called as such:
+ * var obj = Object.create(NumArray).createNew(nums)
+ * var param_1 = obj.sumRange(i,j)
+ */

algorithms/RangeSumQueryImmutable/solution.py

@@ -0,0 +1,27 @@
+class NumArray(object):
+
+    def __init__(self, nums):
+        """
+        :type nums: List[int]
+        """
+        self.sum_map = {}
+        for i in range(0, len(nums)):
+            if i == 0:
+                self.sum_map[i] = nums[i]
+            else:
+                self.sum_map[i] = self.sum_map[i - 1] + nums[i] 
+
+    def sumRange(self, i, j):
+        """
+        :type i: int
+        :type j: int
+        :rtype: int
+        """
+        if i == 0:
+            return self.sum_map[j]
+        return self.sum_map[j] - self.sum_map[i - 1]
+
+
+# Your NumArray object will be instantiated and called as such:
+# obj = NumArray(nums)
+# param_1 = obj.sumRange(i,j)