Added solution for 1876

Author: chirag64

01876. Substrings of Size Three with Distinct Characters.rs

@@ -0,0 +1,21 @@
+impl Solution {
+    // Loop through string and create substrings of size 3 along the way. Compare and make sure each character in substring is unique. If it is add 1 to the result
+    pub fn count_good_substrings(s: String) -> i32 {
+        let len = s.len();
+        let mut substrings = 0;
+        
+        if len > 2 {
+            for c in 0..(len - 2) {
+                let first_char = s.chars().nth(c).unwrap();
+                let second_char = s.chars().nth(c + 1).unwrap();
+                let third_char = s.chars().nth(c + 2).unwrap();
+
+                if (first_char != second_char) && (second_char != third_char) && (third_char != first_char) {
+                    substrings += 1;
+                } 
+            }
+        }
+        
+        return substrings;
+    }
+}