又見二進制（簡單DFS）

#include <iostream>
#include <cstdio>
#include <cmath>
using namespace std;
bool did = false;
void dfs(int n,int x) {
	if (n < 0)
		return;
	else if (n == 0 && !did) {
		cout << 0 << endl;
		return;
	}
	else if (n == 0 && did) {
		cout << 0 << ")";
		return;
	}
	else if (n == 1 && did)
		return;
	int sum = 0;
	int m;
	int k = n;
	int i;
	for ( i = 0; ; i++) {
		m = pow(2, i);
		if (m > k)
		{
			cout << 2;
			did = true;
			sum += pow(2, i - 1);
			k = n - sum;
			if (i != 2)
				cout << "(";
			dfs(i - 1,x);
			if (k != 0)
				cout << "+";
			i = 0;
			if (k == 0)
				break;
		}
	}
	if(x != sum)
	cout << ")";
}
int main() {
	int n;
	cin >> n;
	dfs(n,n);
	return 0;
}