101 lines
3.1 KiB
C++
101 lines
3.1 KiB
C++
// Source : https://leetcode.com/problems/most-common-word/
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// Author : Hao Chen
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// Date : 2018-04-19
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/***************************************************************************************
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*
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* Given a paragraph and a list of banned words, return the most frequent word that is
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* not in the list of banned words. It is guaranteed there is at least one word that
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* isn't banned, and that the answer is unique.
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*
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* Words in the list of banned words are given in lowercase, and free of punctuation.
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* Words in the paragraph are not case sensitive. The answer is in lowercase.
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*
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*
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* Example:
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* Input:
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* paragraph = "Bob hit a ball, the hit BALL flew far after it was hit."
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* banned = ["hit"]
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* Output: "ball"
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* Explanation:
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* "hit" occurs 3 times, but it is a banned word.
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* "ball" occurs twice (and no other word does), so it is the most frequent non-banned
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* word in the paragraph.
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* Note that words in the paragraph are not case sensitive,
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* that punctuation is ignored (even if adjacent to words, such as "ball,"),
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* and that "hit" isn't the answer even though it occurs more because it is banned.
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*
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*
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*
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*
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* Note:
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*
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*
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* 1 <= paragraph.length <= 1000.
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* 1 <= banned.length <= 100.
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* 1 <= banned[i].length <= 10.
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* The answer is unique, and written in lowercase (even if its occurrences in
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* paragraph may have uppercase symbols, and even if it is a proper noun.)
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* paragraph only consists of letters, spaces, or the punctuation symbols !?',;.
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* Different words in paragraph are always separated by a space.
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* There are no hyphens or hyphenated words.
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* Words only consist of letters, never apostrophes or other punctuation
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* symbols.
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*
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*
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*
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***************************************************************************************/
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class Solution {
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private:
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bool isLetter(char c) {
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return c >= 'a' && c <= 'z';
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}
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public:
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string mostCommonWord(string paragraph, vector<string>& banned) {
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unordered_map<string, int> banned_map, words_map;
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for (auto w:banned) {
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banned_map[w]++;
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}
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//conert the string to lower case.
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transform(paragraph.begin(), paragraph.end(), paragraph.begin(), ::tolower);
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//transfer the symbols to space.
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for (int i=0; i<paragraph.size(); i++) {
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if ( !isLetter(paragraph[i]) ){
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paragraph[i] = ' ';
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}
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}
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string word;
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for(auto c:paragraph) {
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if (isLetter(c)) {
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word += c;
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}else{
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if ( word.size()>0 ) {
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words_map[word]++;
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}
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word="";
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}
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}
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if ( word.size()>0 ) words_map[word]++;
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string result;
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int max_cnt=0;
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// go through the words_map
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for (auto const& w : words_map) {
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if ( banned_map.find(w.first) != banned_map.end() ) {
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continue;
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}
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if (max_cnt < w.second) {
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result = w.first;
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max_cnt = w.second;
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}
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}
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return result;
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}
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};
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