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Short Encoding of Words in C++
Suppose we have a list of words, we may encode it by writing a reference string S and a list of indexes A. So for example, let us consider if the list of words is ["time", "me", "bell"], then we can write it as S = "time#bell#" and indexes = [0, 2, 5]. Here for each index, we will recover the word by reading from the reference string from that index until we reach the "#" symbol.
So we have to find what is the length of the shortest reference string S possible that encodes the given words? So for the given example, the output will be 10.
To solve this, we will follow these steps −
- Define insertNode method, this will take head and string s
- curr := head, flag := false.
- for i in range size of s – 1 down to 0
- x := s[i]
- if m[x] of curr is null, then set flat := true and create a new node, into m[x] of curr.
- curr := m[x] of curr
- return size of s when flag is true, otherwise 0
- From the main method, do the following −
- ret := 0, head := new node
- sort the words array based on their length
- n := size of words
- for i in range 0 to n – 1
- temp := insertNode(head, words[i])
- if temp is non 0, then ret := ret + temp + 1
- return ret.
Let us see the following implementation to get better understanding −
Example
#include <bits/stdc++.h>
using namespace std;
struct Node{
map <char, Node*> m;
};
class Solution {
public:
static bool cmp(string a, string b){
return a.size() > b.size();
}
int insertNode(Node* head, string s){
Node* curr = head;
bool flag = false;
for(int i = s.size() - 1; i >= 0; i--){
char x = s[i];
if(!curr->m[x]){
flag = true;
curr->m[x] = new Node();
}
curr = curr->m[x];
}
return flag? (int)s.size() : 0;
}
int minimumLengthEncoding(vector<string>& words) {
int ret = 0;
Node* head = new Node();
sort(words.begin(), words.end(), cmp);
int n = words.size();
for(int i = 0; i < n; i++){
int temp= insertNode(head, words[i]);
if(temp){
ret += (temp + 1);
}
}
return ret;
}
};
main(){
vector<string> v = {"time", "me", "bell"};
Solution ob;
cout << (ob.minimumLengthEncoding(v));
}Input
["time", "me", "bell"]
Output
10
Updated on: 04-May-2020
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