C语言 | Leetcode C语言题解之第393题UFT-8编码验证

题目：

题解：

static const int MASK1 = 1 << 7;
static const int MASK2 = (1 << 7) + (1 << 6);

bool isValid(int num) {
    return (num & MASK2) == MASK1;
}

int getBytes(int num) {
    if ((num & MASK1) == 0) {
        return 1;
    }
    int n = 0;
    int mask = MASK1;
    while ((num & mask) != 0) {
        n++;
        if (n > 4) {
            return -1;
        }
        mask >>= 1;
    }
    return n >= 2 ? n : -1;
}

bool validUtf8(int* data, int dataSize){
    int m = dataSize;
    int index = 0;
    while (index < m) {
        int num = data[index];
        int n = getBytes(num);
        if (n < 0 || index + n > m) {
            return false;
        }
        for (int i = 1; i < n; i++) {
            if (!isValid(data[index + i])) {
                return false;
            }
        }
        index += n;
    }
    return true;
}