Leetcode: Word Break @Python

class Solution:
    # @param s, a string
    # @param dict, a set of string
    # @return a boolean
    def wordBreak(self, s, dict):
        n=len(s)
        dp=[False for i in range(n)]
        for i in range(1,n+1):
            if s[:i] in dict:
                dp[i-1]=True
            for j in range(1,i):
                if dp[j-1] and s[j:i] in dict:
                    dp[i-1]=True
        return dp[n-1] if n>0 else '' in dict