算法设计与应用基础系列11


Word Break

Given a non-empty string s and a dictionary wordDict containing a list of non-empty words, determine
if s can be segmented into a space-separated sequence of one or more dictionary words. You may assume the dictionary does not contain duplicate words.

For example, given
s = 

"leetcode"

,
dict = 

["leet", "code"]

.

Return true because 

"leetcode"

 can be segmented as 

"leet
code"

.

bool wordBreak(string s, unordered_set<string> &dict) {
if(dict.size()==0) return false;

vector<bool> dp(s.size()+1,false);
dp[0]=true;

for(int i=1;i<=s.size();i++)
{
for(int j=i-1;j>=0;j--)
{
if(dp[j])
{
string word = s.substr(j,i-j);
if(dict.find(word)!= dict.end())
{
dp[i]=true;
break; //next i
}
}
}
}

return dp[s.size()];
}