LeetCode:Word Break(DP)

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"

.

分析：设状态为f(i),表示s[0,i]是否可以分词，则状态转移方程为

　　f(i)=any_of(f(j)&&s[j+1,i]属于wordDict); 0<=j<i

class Solution {
public:
bool wordBreak(string s, unordered_set<string>& wordDict) {
vector<bool> f(s.size()+1,false);
f[0]=true;

for(int i=1;i<=s.size();++i)
for(int j=i-1;j>=0;--j)
if(f[j]&&wordDict.find(s.substr(j,i-j))!=wordDict.end())
{
f[i]=true;
break;
}
return f[s.size()];

}
};