硬币问题--回溯解法

#include<iostream>
#include<vector>
#include<algorithm>
#include <cmath>
using namespace std;

class Solution {
private:
	vector<vector<int>> res;
	int sum = 0;
	void process(const vector<int>& input, vector<int>temp, int target, int index) {
		if (sum == target) {
			res.push_back(temp);
			return;
		}
		if (sum > target)
			return;
		for (int i = index; i < input.size(); ++i) {
			sum += input[i];
			temp.push_back(input[i]);
			process(input, temp, target, i+1);
			sum -= input[i];
			temp.pop_back();
		}
	}
public:
	vector<vector<int>>get_combination(vector<int>input, int target) {
		if (input.size() == 0)
			return res;
		sum = 0;
		vector<int> temp;
		sort(input.begin(), input.end());
		process(input,temp,target,0);
		return res;
	}
};
int main() {
	vector<int> input = { 4,5,7,3,1};
	Solution* ptr = new Solution();
	vector<vector<int>> res = ptr->get_combination(input, 10);
	for (int i = 0; i < res.size(); ++i) {
		for (int j = 0; j < res[i].size(); ++j) {
			cout << res[i][j];
		}
		cout << endl;
	}
}