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// 2707. Extra Characters in a String
#include "leetcode.h"
/*
* you are given a 0-indexed string 's' and a dictionary of words 'dictionary'.
* you have to break 's' into one or more non-overlapping substrings that each
* substring is present in 'dictionary'. there may be some extra characters in
* 's' which are not present in any of the substrings. return the minimum number
* of extra characters left over if you break up 's' optimally
*/
class Solution {
int mod = 1e7 + 7;
int hash_func(string s) {
int res = 0;
for (auto i : s)
res = (res * 27 + i - 'a' + 1) % mod;
return res;
}
int min_cost(int l, vector<int> &dp, string s, unordered_set<int> &d) {
if (l == s.size())
return 0;
if (dp[l] != -1)
return dp[l];
int res = 1 + min_cost(l + 1, dp, s, d), curr = 0;
for (int i = l; i < s.size(); i++) {
curr = (curr * 27 + s[i] - 'a' + 1) % mod;
if (d.find(curr) != d.end())
res = min(res, min_cost(i + 1, dp, s, d));
}
return dp[l] = res;
}
public:
int minExtraChar(string s, vector<string> &dictionary) {
unordered_set<int> d;
for (auto i : dictionary)
d.insert(hash_func(i));
vector<int> dp(s.size(), -1);
return min_cost(0, dp, s, d);
}
};
int main() {
Solution obj;
string s1 = "leetscode", s2 = "sayhelloworld";
vector<string> d1 = {"leet", "code", "leetcode"}, d2 = {"hello", "world"};
printf("%d\n", obj.minExtraChar(s1, d1)); // expepct: 1
printf("%d\n", obj.minExtraChar(s2, d2)); // expepct: 3
}
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