[LeetCode]UTF-8 Validation

关于UTF-8的介绍请参考这篇文章，只要按照UTF-8的格式check即可。注意虽然UTF-8目前的最大值为0x10FF，这一题不需要check，check的话过不了test case。代码如下：

	class Solution {
	public:
	bool validUtf8(vector<int>& data) {
	const int MOD = 256;
	int i = 0, len = data.size();
	while (i < len)
	{
	int byte = data[i] % MOD;
	int k = 0;
	while (k >= 0 && byte >> (7 - k) & 1)++k;
	if (k == 1 || k > 4)return false;
	//unicode max value 0010 FFFF
	//if (k == 4 && byte % 8 > 4)return false;
	while (--k > 0)
	{
	++i;
	if (i >= len)return false;
	int nextByte = data[i] % MOD;
	if ((nextByte >> 7 & 1) == 0 || nextByte >> 6 & 1)return false;
	}
	++i;
	}
	return true;
	}
	};

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