leetcode 日经贴，Cpp code -Word Break II

class Solution {
public:
void genvs(const string &s, const vector<vector<int> > &dp, int p, string cs, vector<string> &vs, const vector<int> &valid) {
int n = s.length();
if (p == n) {
vs.push_back(cs);
return ;
}
string delimiter = p == 0? "":" ";
for (int i = p; i < n; ++i) {
if (dp[p][i] && valid[i + 1]) {
genvs(s, dp, i + 1, cs + delimiter + s.substr(p, i  - p + 1), vs, valid);
}
}
}
vector<string> wordBreak(string s, unordered_set<string>& wordDict) {
int n = s.length();
vector<vector<int> > dp;
dp.resize(n);
for (int i = 0; i < n; ++i) {
dp[i].resize(n);
}
//init dp matrix
for (int i = 0; i < n; ++i) {
for (int j = i; j < n; ++j) {
string subs = s.substr(i, j - i + 1);
if (wordDict.find(subs) != wordDict.end()) {
dp[i][j] = 1;
}
}
}
vector<int> valid(n + 1);
valid
= 1;
for (int i = n - 1; i >= 0; --i) {
if (valid[i + 1]) {
for (int j = 0; j <= i; ++j) {
if (dp[j][i]) {
valid[j] = 1;
}
}
}
}
vector<string> ans;
genvs(s, dp, 0, "", ans, valid);
return ans;
}
};