From bb7f9375daaad6899e7158054bc7f5bfc1704dc7 Mon Sep 17 00:00:00 2001
From: ShusenTang <tangshusen@pku.edu.cn>
Date: Wed, 1 Jan 2020 19:40:52 +0800
Subject: [PATCH] Create 393. UTF-8 Validation.md

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 solutions/393. UTF-8 Validation.md | 42 ++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 solutions/393. UTF-8 Validation.md

diff --git a/solutions/393. UTF-8 Validation.md b/solutions/393. UTF-8 Validation.md
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+# [393. UTF-8 Validation](https://leetcode.com/problems/utf-8-validation/)
+# 思路
+
+此题让我们验证给定的编码是否是合法的 UTF-8 编码。
+
+此题感觉没啥好说的，按照题目进行验证即可，详见代码。
+
+**需要注意的是题目给的是【单个字符】的UTF-8规则，而实际却让我们判断的是【字符序列】** 估计这也是为什么那么多人给此题倒赞吧....实属坑题
+
+# C++
+``` C++
+class Solution {
+private:
+    int pre_1(int n){ // 计算有多少个前导1
+        int mask = 128;
+        int res = 0;
+        while(mask & n){
+            res++;
+            mask >>= 1;
+        }
+        return res;
+    }
+public:
+    bool validUtf8(vector<int>& data) {
+        int i = 0;
+        # define start_with_10(n) ((n & 0x000000c0) == 128)
+        while(i < data.size()){
+            int num_pre1 = pre_1(data[i]);
+            if(!num_pre1) i++; 
+            else{
+                if(num_pre1 == 1 || num_pre1 > 4) return false;
+                for(int j = 1; j < num_pre1; j++){
+                    if(j + i == data.size() || !start_with_10(data[j+i]))
+                        return false;
+                }
+                i += num_pre1;
+            }
+        }
+        return true;   
+    }
+};
+```