add utf_8_validation (#29)

Author: 0xmountaintop

README.md

@@ -66,7 +66,7 @@ cargo test
 0318| [Maximum Product of Word Lengths](https://leetcode.com/problems/maximum-product-of-word-lengths/) | [C++](https://github.com/kamyu104/LeetCode-Solutions/blob/master/C++/maximum-product-of-word-lengths.cpp) [Python](https://github.com/kamyu104/LeetCode-Solutions/blob/master/Python/maximum-product-of-word-lengths.py) <br>------</br> [Rust](./kamyu104/src/maximum_product_of_word_lengths.rs) | _O(n)_ ~ _O(n^2)_ |  _O(n)_ | Medium         || Bit Manipulation, Counting Sort, Pruning|
 0342 | [Power of Four](https://leetcode.com/problems/power-of-four/) | [C++](https://github.com/kamyu104/LeetCode-Solutions/blob/master/C++/power-of-four.cpp) [Python](https://github.com/kamyu104/LeetCode-Solutions/blob/master/Python/power-of-four.py) <br>------</br> [Rust](./kamyu104/src/power_of_four.rs) | _O(1)_ | _O(1)_ | Easy | |
 0371 | [Sum of Two Integers](https://leetcode.com/problems/sum-of-two-integers/) | [C++](https://github.com/kamyu104/LeetCode-Solutions/blob/master/C++/sum-of-two-integers.cpp) [Python](https://github.com/kamyu104/LeetCode-Solutions/blob/master/Python/sum-of-two-integers.py) <br>------</br> [Rust](./kamyu104/src/sum_of_two_integers.rs) | _O(1)_ | _O(1)_ | Easy | LintCode |
-0389 | [Find the Difference](https://leetcode.com/problems/find-the-difference/) | [C++](https://github.com/kamyu104/LeetCode-Solutions/blob/master/C++/find-the-difference.cpp) [Python](https://github.com/kamyu104/LeetCode-Solutions/blob/master/Python/find-the-difference.py) <br>------</br> [Rust](./kamyu104/src/find_the_difference.rs) | _O(n)_ | _O(1)_ | Easy | |
+0389 | [~~Find the Difference~~](https://leetcode.com/problems/find-the-difference/) | [C++](https://github.com/kamyu104/LeetCode-Solutions/blob/master/C++/find-the-difference.cpp) [Python](https://github.com/kamyu104/LeetCode-Solutions/blob/master/Python/find-the-difference.py) <br>------</br> [Rust](./kamyu104/src/find_the_difference.rs) | _O(n)_ | _O(1)_ | Easy | |
 0393 | [UTF-8 Validation](https://leetcode.com/problems/utf-8-validation/) | [C++](https://github.com/kamyu104/LeetCode-Solutions/blob/master/C++/utf-8-validation.cpp) [Python](https://github.com/kamyu104/LeetCode-Solutions/blob/master/Python/utf-8-validation.py) <br>------</br> [Rust](./kamyu104/src/utf_8_validation.rs) | _O(n)_ | _O(1)_ | Medium | |
 
 <!-- 

kamyu104/src/main.rs

@@ -1,4 +1,5 @@
 mod bitwise_and_of_numbers_range;
+mod find_the_difference;
 mod maximum_product_of_word_lengths;
 mod missing_number;
 mod number_of_1_bits;
@@ -9,6 +10,5 @@ mod single_number;
 mod single_number_ii;
 mod single_number_iii;
 mod sum_of_two_integers;
-mod find_the_difference;
-mod utf_8_validation;
 mod template;
+mod utf_8_validation;

kamyu104/src/utf_8_validation.rs

@@ -0,0 +1,41 @@
+// Time:  O(n)
+// Space: O(1)
+pub struct Solution {}
+impl Solution {
+    pub fn valid_utf8(data: Vec<i32>) -> bool {
+        let mut count: i32 = 0;
+        for c in data {
+            match count {
+                0 => {
+                    if (c >> 5) == 0b110 {
+                        count = 1;
+                    } else if (c >> 4) == 0b1110 {
+                        count = 2;
+                    } else if (c >> 3) == 0b11110 {
+                        count = 3;
+                    } else if c >> 7 != 0 {
+                        return false;
+                    }
+                }
+                _ => {
+                    if (c >> 6) != 0b10 {
+                        return false;
+                    }
+                    count -= 1;
+                }
+            }
+        }
+        count == 0
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_valid_utf8() {
+        assert_eq!(Solution::valid_utf8(vec![197, 130, 1]), true);
+        assert_eq!(Solution::valid_utf8(vec![235, 140, 4]), false);
+    }
+}