Array Combination | tech::interview


Array Combination | tech::interview
给了a, b, c三个vector<string>,要求求出数组的Combination,每一个vector中选一个,为空则不选,不用考虑duplicate。
G家题,本来是极其简单的,直接三重循环搞定就好,但是如果有个数组是空的那就不行了。
用递归的方法写了下,能比iterative的清晰很多。考虑空数组的话,三重循环做也可以但是会比较难看。
而且下面的方法也容易扩展成k个数组的情况。

using array = vector<int>;
vector<array> arr_comb(const array& a, const array& b, const array& c) {
vector<array> ret;
array sln;
const array* arrs[] = {&a,&b,&c};
function<void(int)> solve = [&](int arr_id) {
if(arr_id == 3) {
ret.push_back(sln);
return;
} else if(arrs[arr_id]->empty()) {
solve(arr_id+1);
} else {
for(int i = 0; i < arrs[arr_id]->size(); ++i) {
sln.push_back(arrs[arr_id]->at(i));
solve(arr_id+1);
sln.pop_back();
}
}
};
solve(0);
return ret;
}

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