CCF201809-4 再卖菜 记忆化搜索

/*
					_ooOoo_
					o8888888o
					88" . "88
					(| -_- |)
					O\  =  /O
				____/`---'\____
				.'  \\|     |//  `.
			/  \\|||  :  |||//  \
			/  _||||| -:- |||||-  \
			|   | \\\  -  /// |   |
			| \_|  ''\---/''  |   |
			\  .-\__  `-`  ___/-. /
			___`. .'  /--.--\  `. . __
		."" '<  `.___\_<|>_/___.'  >'"".
		| | :  `- \`.;`\ _ /`;.`/ - ` : | |
		\  \ `-.   \_ __\ /__ _/   .-` /  /
======`-.____`-.___\_____/___.-`____.-'======
					`=---='
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
			佛祖保佑       永无BUG
*/
#include 
#define MAX 305
using namespace std;

int n, a[MAX], b[MAX];
int m[MAX][MAX][MAX];
int flag;

void init()
{
	flag = 0;
	memset(m, 0, sizeof(m));
}

void print()
{
	for (int i = 1; i <= n; i++) {
		if (i != 1) cout << " ";
		cout << b[i];
	}
	cout << endl;
}

void dfs(int index)
{
	if (m[index][b[index - 1]][b[index - 2]]) return;
	print();
	m[index][b[index - 1]][b[index - 2]] = 1;

	if (index == n) {
		int x = 3 * a[index - 1] - b[index - 1] - b[index - 2];
		for (int i = 0; i < 3; i++) {
			if (x + i <= 0) continue;
			b[n] = x + i;
			if ((b[n] + b[n - 1] + b[n - 2]) / 3 == a[n - 1]) {
				if ((b[n] + b[n - 1]) / 2 == a[n]) {
					print();
					exit(0);
				}
			}
		}
		return;
	}

	int x = 3 * a[index - 1] - b[index - 1] - b[index - 2];
	
	for (int i = 0; i < 3; i++) {
		if (x + i <= 0) continue;
		b[index] = x + i;
		if ((b[index] + b[index - 1] + b[index - 2]) / 3 == a[index - 1]) dfs(index + 1);
	}
}

int main()
{
	cin >> n;
	for (int i = 1; i <= n; i++) cin >> a[i];
	for (int i = 1; i <= 2 * a[1]; i++) {
		b[1] = i;
		b[2] = 2 * a[1] - b[1];
		if ((b[1] + b[2]) / 2 == a[1]) dfs(3);
		b[2] = 2 * a[1] - b[1] + 1;
		if ((b[1] + b[2]) / 2 == a[1]) dfs(3);
	}
	return 0;
}