【搜索】POJ-3050 基础DFS

一、题目

Description

The cows play the child's game of hopscotch in a non-traditional way. Instead of a linear set of numbered boxes into which to hop, the cows create a 5x5 rectilinear grid of digits parallel to the x and y axes. 

They then adroitly hop onto any digit in the grid and hop forward, backward, right, or left (never diagonally) to another digit in the grid. They hop again (same rules) to a digit (potentially a digit already visited). 

With a total of five intra-grid hops, their hops create a six-digit integer (which might have leading zeroes like 000201). 

Determine the count of the number of distinct integers that can be created in this manner.

Input

* Lines 1..5: The grid, five integers per line

Output

* Line 1: The number of distinct integers that can be constructed

Sample Input

1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
1 1 1 2 1
1 1 1 1 1

Sample Output

15

Hint

OUTPUT DETAILS: 

111111, 111112, 111121, 111211, 111212, 112111, 112121, 121111, 121112, 121211, 121212, 211111, 211121, 212111, and 212121 can be constructed. No other values are possible.

二、思路&心得

• 利用set集合保证数据不重复，最后直接输出set的大小即可
• 基础深搜，数据量较弱

三、代码

#include<cstdio>
#include<set>
#define MAX_SIZE 5
using namespace std;

set<int> s;

int N, M;

int a[10];

int map[MAX_SIZE][MAX_SIZE];

int dirction[4][2] = {0, -1, -1, 0, 0, 1, 1, 0};

bool isLegal(int x, int y) {
	if (x >= 0 && x < MAX_SIZE && y >= 0 && y < MAX_SIZE) return true;
	else return false;
}

void dfs(int x, int y, int k) {
	if (k == 6) {
		int num = a[0];
		for (int j = 1; j < 6; j ++) {
			num = num * 10 + a[j];
		}
		s.insert(num);
		return;
	}
	for(int i = 0; i < 4; i ++) {
		int tx = x + dirction[i][0], ty = y + dirction[i][1];
		if (isLegal(tx, ty)) {
			a[k] = map[tx][ty];
			dfs(tx, ty, k + 1);
		}
	}
} 

int main() {
	for (int i = 0; i < 5; i ++) {
		for (int j = 0; j < 5; j ++) {
			scanf("%d", &map[i][j]);
		}
	}
	for (int i = 0; i < 5; i ++) {
		for (int j = 0; j < 5; j ++) {
			a[0] = map[i][j];
			dfs(i, j, 1);
		}
	}
	printf("%d", s.size());
	return 0;
}