标签：efi tmp maps star void child insert integer ios
Implement a MapSum class with insert, and sum methods.
For the method insert, you‘ll be given a pair of (string, integer). The string represents the key and the integer represents the value. If the key already existed, then the original key-value pair will be overridden to the new one.
For the method sum, you‘ll be given a string representing the prefix, and you need to return the sum of all the pairs‘ value whose key starts with the prefix.
Example 1:
Input: insert("apple", 3), Output: Null
Input: sum("ap"), Output: 3
Input: insert("app", 2), Output: Null
Input: sum("ap"), Output: 5
Runtime: 0 ms, faster than 100.00% of C++ online submissions for Map Sum Pairs.
Trie简单题。
#include <assert.h>
#include <map>
#include <iostream>
#include <vector>
#include <unordered_map>
#include <algorithm>
#define ALL(x) (x).begin(), (x).end()
using namespace std;
struct TrieNode{
TrieNode* children[26];
string word;
int sum;
TrieNode(){
for(int i=0; i<26; i++) children[i] = nullptr;
word = "";
sum = 0;
}
};
class Trie{
TrieNode* root;
public:
Trie(){
root = new TrieNode();
}
explicit Trie(vector<string> words, vector<int> value){
root = new TrieNode();
buildtrie(words, value);
}
void buildtrie(vector<string>& words, vector<int>& value){
for(int i=0; i<words.size(); i++){
TrieNode* tmp = root;
for(int j=0; j<words[i].size(); j++){
int idx = words[i][j] - ‘a‘;
if(!tmp->children[idx]) tmp->children[idx] = new TrieNode();
tmp = tmp->children[idx];
tmp->sum += value[i];
}
tmp->word = words[i];
}
}
int getprefixsum(string prefix){
TrieNode* tmp = root;
for(int i=0; i<prefix.size(); i++){
int idx = prefix[i] - ‘a‘;
if(!tmp->children[idx]) return 0;
tmp = tmp->children[idx];
}
return tmp->sum;
}
};
class MapSum {
private:
unordered_map<string, int> mp;
Trie trie;
public:
/** Initialize your data structure here. */
MapSum() {
trie = Trie();
}
void insert(string key, int val) {
if(!mp.count(key)){
mp[key] = val;
vector<string> words = {key};
vector<int> valvec = {val};
trie.buildtrie(words,valvec);
}else{
vector<string> words = {key};
vector<int> valvec = {val - mp[key]};
trie.buildtrie(words, valvec);
}
}
int sum(string prefix) {
return trie.getprefixsum(prefix);
}
};
标签：efi tmp maps star void child insert integer ios
原文地址：https://www.cnblogs.com/ethanhong/p/10191225.html
