摘要：private static String convertBinary(int sum) { StringBuffer binary = new StringBuffer(); while (true) { binary.insert(0, sum % 2); sum = sum / 2... 阅读全文

摘要：方法2：进一步的方法是用HashSet, 每次取长度为10的字符串，O(N)时间遍历数组，重复就加入result，但这样需要O(N)的space, 准确说来O(N*10bytes), java而言一个char是2 bytes，所以O(N*20bytes)。String一大就MLE 最优解：是在方法2 阅读全文

摘要：Given an array containing n distinct numbers taken from 0, 1, 2, ..., n, find the one that is missing from the array. For example, Given nums = [0, 1, 3] return 2. Note: Your algorithm should run i... 阅读全文

摘要：A binary watch has 4 LEDs on the top which represent the hours (0-11), and the 6 LEDs on the bottom represent the minutes (0-59). Each LED represents 阅读全文