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59 lines (55 loc) · 1.56 KB
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//
// Solution17.cpp
// Algorithm
//
// Created by Pancf on 2019/12/3.
// Copyright © 2019 Pancf. All rights reserved.
//
#include "Solution17.hpp"
//vector<string> Solution17::letterCombinations(string digits) {
// vector<string> rv;
// if (digits.empty()) {
// return rv;
// }
// rv.push_back("");
// const vector<string> v = {"", "", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"};
// for (auto ch : digits) {
// if (ch < '2' || ch > '9') {
// continue;
// }
// auto candidate = v[ch - '0'];
// if (candidate.empty()) {
// continue;
// }
// vector<string> tmp;
// for (auto candi_ch : candidate) {
// for (auto rv_ch : rv) {
// tmp.push_back(rv_ch + candi_ch);
// }
// }
// rv.swap(tmp);
// }
// return rv;
//}
void dfs(const vector<string>& candidates, vector<string>& rv, string& local, const string dig, int index) {
if (dig.size() == index) {
rv.push_back(local);
} else {
auto candidate = candidates[dig[index] - '0'];
for (auto ch : candidate) {
local.push_back(ch);
dfs(candidates, rv, local, dig, index+1);
local.pop_back();
}
}
}
vector<string> Solution17::letterCombinations(string digits) {
vector<string> rv;
if (digits.empty()) {
return rv;
}
const vector<string> v = {"", "", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"};
string local;
dfs(v, rv, local, digits, 0);
return rv;
}