思路是这种.我们从第一个字符開始向后依次找,直到找到一个断句的地方,使得当前获得的子串在dict中,若找到最后都没找到.那么就是False了. 在找到第一个后,接下来找下一个断句处,当然是从第一个断句处的下一个字符開始找连续的子串,可是这时与第一个就稍有不同.比方说word='ab', dict={ 'a', ab', ...},在找到a后,接下来处理的是b.我们发现b不在dict中,可是我们发现b能够和a结合,形成ab,而ab在dict中.所以这里的每一个子串就能够有三种选择.要么自己单独作为…

Given a string s and a dictionary of words dict, determine if s can be segmented into a space-separated sequence of one or more dictionary words. For example, givens = "leetcode",dict = ["leet", "code"]. Return true because &…

链表的归并排序 超时的代码 class Solution: def merge(self, head1, head2): if head1 == None: return head2 if head2 == None: return head1 # head1 and head2 point to the same link list if head1 == head2: return head1 head = None tail = None # the small pointer point…

Given a string s and a dictionary of words dict, determine if s can be segmented into a space-separated sequence of one or more dictionary words. For example, given s = "leetcode", dict = ["leet", "code"]. Return true because…

Word Break II Given a string s and a dictionary of words dict, add spaces in s to construct a sentence where each word is a valid dictionary word. Return all such possible sentences. For example, givens = "catsanddog",dict = ["cat", &q…

Given a string s and a dictionary of words dict, determine if s can be segmented into a space-separated sequence of one or more dictionary words. For example, givens = "leetcode",dict = ["leet", "code"]. Return true because &…

Reverse digits of an integer. Example1: x = 123, return 321Example2: x = -123, return -321 总结:处理整数溢出的方法 ①用数据类型转换long  或 long long ②在每次循环时先保存下数字变化之前的值,处理后单步恢复看是否相等 (比③好) ③整体恢复,看数字是否相等. 思路:注意30000这样以0结尾的数字,注意越界时返回0. 我检查越界是通过把翻转的数字再翻转回去,看是否相等. int rever…

Write an algorithm to determine if a number is "happy". A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the…

Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order. For example,Given the following matrix: [ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9 ] ] You should return [1,2,3,6,9,8,7,4,5]. 思路:就按照螺旋矩阵的规律 用n记录旋转圈数 每…

Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers. If such arrangement is not possible, it must rearrange it as the lowest possible order (ie, sorted in ascending order). The replaceme…