programming-challenges Playing with Wheels (110902) 题解

一开始居然没想到bfs。

#include <iostream>
#include <sstream>
#include <fstream>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <map>
#include <set>
#include <stack>
#include <assert.h>
#include <algorithm>
#include <math.h>
#include <ctime>
#include <functional>
#include <string.h>
#include <stdio.h>
#include <numeric>
#include <float.h>

using namespace std;

const int MX = 10000; 

vector<bool> visited(MX); 

struct Num {
	int i1, i2, i3, i4; 
	Num() {}
	Num(int ai1, int ai2, int ai3, int ai4) 
		: i1(ai1), i2(ai2), i3(ai3), i4(ai4) {}
	int val() {
		return i4 * 1000 + i3 * 100 + i2 * 10 + i1; 
	}
};
bool operator==(const Num& num1, const Num& num2) {
	return num1.i1 == num2.i1 && num1.i2 == num2.i2 &&
		num1.i3 == num2.i3 && num1.i4 == num2.i4;
}

vector<Num> badNums;
bool check(Num objective, Num num, vector<Num> &nums, vector<bool> &visited, bool &inserted) {
	if (objective == num) return true;

	for (int i = 0; i < badNums.size(); i++) {
		if (num == badNums[i]) {
			return false;
		}
	}

	if (!visited.at(num.val())) {
		visited[num.val()] = true;
		nums.push_back(num);
		inserted = true;
	}
	return false;
} 

int main() {
	int N; cin >> N; 
	for (int i = 0; i < N; i++) {
		int i1, i2, i3, i4; cin >> i1 >> i2 >> i3 >> i4;
		Num current(i1, i2, i3, i4);
		cin >> i1 >> i2 >> i3 >> i4;
		Num objective(i1, i2, i3, i4);

		int badNumber = 0; cin >> badNumber;
		badNums.clear();
		for (int j = 0; j < badNumber; j++) {
			cin >> i1 >> i2 >> i3 >> i4; 
			badNums.push_back(Num(i1, i2, i3, i4)); 
		}

		if (current == objective) {
			cout << 0 << endl;
			continue;
		}

		int times = 0; 
		visited.clear(); visited.resize(MX); 
		vector<Num> bfs[2];
		bfs[0].push_back(current); 

		while (true) {
			times++;
			bool find = false;
			bool inserted = false;
			bfs[times%2].clear();

			for (int j = 0; j < bfs[(times + 1) % 2].size(); j++) {
				Num num = bfs[(times + 1) % 2][j]; 
				Num num1 = num; num1.i1 = (num1.i1 + 1) % 10;
				find = check(objective, num1, bfs[times%2], visited, inserted); 
				if (find) {
					break;
				}
				Num num2 = num; num2.i1 = (num2.i1 + 9) % 10;
				find = check(objective, num2, bfs[times % 2], visited, inserted);
				if (find) {
					break;
				}
				Num num3 = num; num3.i2 = (num3.i2 + 1) % 10;
				find = check(objective, num3, bfs[times % 2], visited, inserted);
				if (find) {
					break;
				}
				Num num4 = num; num4.i2 = (num4.i2 + 9) % 10;
				find = check(objective, num4, bfs[times % 2], visited, inserted);
				if (find) {
					break;
				}
				Num num5 = num; num5.i3 = (num5.i3 + 1) % 10;
				find = check(objective, num5, bfs[times % 2], visited, inserted);
				if (find) {
					break;
				}
				Num num6 = num; num6.i3 = (num6.i3 + 9) % 10;
				find = check(objective, num6, bfs[times % 2], visited, inserted);
				if (find) {
					break;
				}
				Num num7 = num; num7.i4 = (num7.i4 + 1) % 10;
				find = check(objective, num7, bfs[times % 2], visited, inserted);
				if (find) {
					break;
				}
				Num num8 = num; num8.i4 = (num8.i4 + 9) % 10;
				find = check(objective, num8, bfs[times % 2], visited, inserted);
				if (find) {
					break;
				}
			}

			if (find) {
				cout << times << endl; 
				break;
			}
			else if (!inserted) {
				cout << -1 << endl;
				break;
			}
		}

	}

	return 0; 
}