20240318 Finished

src/problem/mod.rs

@@ -77,3 +77,4 @@ mod p2789_largest_element_in_an_array_after_merge_operations;
 mod p2312_selling_pieces_of_wood;
 mod p2684_maximum_number_of_moves_in_a_grid;
 mod p310_minimum_height_trees;
+mod p303_range_sum_query_immutable;

src/problem/p303_range_sum_query_immutable.rs

@@ -0,0 +1,57 @@
+/**
+ * [303] Range Sum Query - Immutable
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+struct NumArray {
+    prefix_array: Vec<i32>,
+}
+
+/**
+ * `&self` means the method takes an immutable reference.
+ * If you need a mutable reference, change it to `&mut self` instead.
+ */
+impl NumArray {
+    fn new(nums: Vec<i32>) -> Self {
+        let mut prefix_array = Vec::with_capacity(nums.len());
+
+        for (index, value) in nums.iter().enumerate() {
+            if index == 0 {
+                prefix_array.push(*value);
+            } else {
+                prefix_array.push(prefix_array[index - 1] + *value);
+            }
+        }
+
+        NumArray { prefix_array }
+    }
+
+    fn sum_range(&self, left: i32, right: i32) -> i32 {
+        let left = left as usize;
+        let right = right as usize;
+
+        return if left == 0 {
+            self.prefix_array[right]
+        } else {
+            self.prefix_array[right] - self.prefix_array[left - 1]
+        };
+    }
+}
+
+/**
+ * Your NumArray object will be instantiated and called as such:
+ * let obj = NumArray::new(nums);
+ * let ret_1: i32 = obj.sum_range(left, right);
+ */
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_303() {}
+}