missing number solution added

2023_09_18/missing_number/src/main.rs

@@ -0,0 +1,10 @@
+// Given an array nums containing n distinct numbers in the range [0, n], return the only number in the range that is missing from the array.
+
+fn missing_number(nums: Vec<i32>) -> i32 {
+    (1..=nums.len() as i32).sum::<i32>() - nums.iter().sum::<i32>()
+}
+
+fn main() {
+    let nums = vec![3, 0, 1];
+    println!("{}", missing_number(nums));
+}