给定一组不同客户的产品评论( R )和包含用_分隔的好词的字符串S ,任务是按照评论的好坏程度从高到低的顺序对其进行排序。
善良值是由该评论中存在的好词的数量定义的。
例子:
Input: S = “geeks_for_geeks_is_great”,
R = {“geeks_are_geeks”, “geeks_dont_lose”, “geeks_for_geeks_is_love”}
Output:
geeks for geeks is love
geeks are geeks
geeks dont lose
Input: S = “cool_wifi_ice”,
R = {“water_is_cool”, “cold_ice_drink”, “cool_wifi_speed”}
Output:
cool wifi speed
water is cool
cold ice drink
幼稚的方法:将所有好的单词插入unordered_set中,然后遍历reviews数组的每个句子的每个单词,并通过检查该单词是否在该组好的单词中来保留这些单词的数量。然后,我们使用稳定的排序算法,并根据R中存在的每个评论中的好的单词数对数组R进行排序。很明显,此方法的时间复杂度大于O(N * NlogN) 。
高效的方法:对所有好的单词进行一次Trie,并使用Trie在评论中检查每个单词的优劣。
- 插入所有好的单词。
- 对于每个评论,通过检查给定单词是否存在于特里来计算其中的好单词数量。
下面是上述方法的实现:
// C++ implementation of the approach
#include
using namespace std;
#define F first
#define S second
#define MAX 26
// Comparator function for sorting
bool cmp(const pair& a, const pair& b)
{
// Compare the number of good words
if (a.F == b.F)
return a.S < b.S;
return a.F > b.F;
}
// Structure of s Trie node
struct node {
bool exist;
node* arr[MAX];
node(bool bul = false)
{
exist = bul;
for (int i = 0; i < MAX; i++)
arr[i] = NULL;
}
};
// Function to add a string to the trie
void add(string s, node* trie)
{
// Add a node to the trie
int n = s.size();
for (int i = 0; i < n; i++) {
// If trie doesn't already contain
// the current node then create one
if (trie->arr[s[i] - 'a'] == NULL)
trie->arr[s[i] - 'a'] = new node();
trie = trie->arr[s[i] - 'a'];
}
trie->exist = true;
return;
}
// Function that returns true if
// the trie contains the string s
bool search(string s, node* trie)
{
// Search for a node in the trie
for (int i = 0; i < s.size(); i++) {
if (trie->arr[s[i] - 'a'] == NULL)
return false;
trie = trie->arr[s[i] - 'a'];
}
return trie->exist;
}
// Function to replace every '_' with a
// white space in the given string
void convert(string& str)
{
// Convert '_' to spaces
for (int i = 0; i < str.size(); i++)
if (str[i] == '_')
str[i] = ' ';
return;
}
// Function to sort the array based on good words
void sortArr(string good, vector& review)
{
// Extract all the good words which
// are '_' separated
convert(good);
node* trie = new node();
string word;
stringstream ss;
ss << good;
// Building the entire trie by stringstreaming
// the 'good words' string
while (ss >> word)
add(word, trie);
int k, n = review.size();
// To store the number of good words
// and the string index pairs
vector > rating(n);
for (int i = 0; i < n; i++) {
convert(review[i]);
ss.clear();
ss << review[i];
k = 0;
while (ss >> word) {
// If this word is present in the trie
// then increment its count
if (search(word, trie))
k++;
}
// Store the number of good words in the
// current string paired with its
// index in the original array
rating[i].F = k;
rating[i].S = i;
}
// Using comparator function to
// sort the array as required
sort(rating.begin(), rating.end(), cmp);
// Print the sorted array
for (int i = 0; i < n; i++)
cout << review[rating[i].S] << "\n";
}
// Driver code
int main()
{
// String containing good words
string S = "geeks_for_geeks_is_great";
// Vector of strings to be sorted
vector R = { "geeks_are_geeks", "geeks_dont_lose",
"geeks_for_geeks_is_love" };
// Sort the array based on the given conditions
sortArr(S, R);
}
输出:
geeks for geeks is love
geeks are geeks
geeks dont lose