[leetcode]Word Break @ Python

原題地址：https://oj.leetcode.com/problems/word-break/

題意：

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 "leetcode" can be segmented as "leet code".

解題思路：這道題考察的顯然不是dfs，為什么？因為這道題不需要給出如何分割的答案，只需要判斷是否可以分割為字典中的單詞即可。我們考慮使用動態規划，這個思路看代碼的話不難，用python寫起來也比較清晰。

代碼：

class Solution:
    # @param s, a string
    # @param dict, a set of string
    # @return a boolean
    # @good coding!
    def wordBreak(self, s, dict):
        dp = [False for i in range(len(s)+1)]
        dp[0] = True
        for i in range(1, len(s)+1):
            for k in range(i):
                if dp[k] and s[k:i] in dict:
                    dp[i] = True
        return dp[len(s)]