uva 1419 Ugly Windows

题目链接: 点击打开链接

题目大意: 输入几个窗口,判断在最顶上的窗口是哪些

思路: 字符串遍历

分析: 

思路应该没问题.poj上是AC了,但是uva上提交了半天都是wa,上网找了几个代码交上去也是wa...从uva上找了几道之前AC的题,原本可以的代码也都wa了...是不是出了什么问题?

1. 第一步先把不可能在顶端的窗口过滤掉.观察在边界上的字母,如果没被覆盖,周围一定有两个相同字母,找不到说明有窗口overlap了...

2. 还有一种可能是一个小窗口完全叠加在一个大窗口上.这种情况下只要扫描大窗口内部,发现一个不是'.'的字母就可以排除了.

代码:

#include <cstdio>
#include <memory.h>
using namespace std;

const int maxn = 100 + 10;
char ui[maxn][maxn];
int n, m;
bool possible[27], input[27];

struct area
{
	int x1, y1, x2, y2;
} areas[27];

bool inside(int x, int y)
{
	return 0 <= x && x < n && 0 <= y && y < m;
}

bool is_cutted(int x, int y)
{
	char c = ui[x][y];
	int total = 0;
	if (inside(x-1, y) && ui[x-1][y] == c)
		++total;
	if (inside(x+1, y) && ui[x+1][y] == c)
		++total;
	if (inside(x, y-1) && ui[x][y-1] == c)
		++total;
	if (inside(x, y+1) && ui[x][y+1] == c)
		++total;
	return total < 2;
}

bool is_upper_left(int x, int y)
{
	char c = ui[x][y];
	return inside(x, y+1) && ui[x][y+1] == c && 
			inside(x+1, y) && ui[x+1][y] == c;
}

bool is_lower_right(int x, int y)
{
	char c = ui[x][y];
	return inside(x, y-1) && ui[x][y-1] == c && 
			inside(x-1, y) && ui[x-1][y] == c;
}

void init()
{
	for (int i = 0; i < n; ++i)
		scanf("%s", ui[i]);
		//for (int j = 0; j < m; ++j) {
		//	scanf("%c", &ui[i][j]);
		//	printf("%c", ui[i][j]);
		//}
	memset(possible, 1, sizeof(possible));
	memset(input, 0, sizeof(input));
}

void find_cutted()
{
	for (int i = 0; i < n; ++i)
		for (int j = 0; j < m; ++j) {
			char c = ui[i][j];
			if (c!= '.')
			{
				input[c - 'A'] = true;
				if (possible[c - 'A']) {
					if (is_upper_left(i, j)) {
						areas[c - 'A'].x1 = i;
						areas[c - 'A'].y1 = j;
					}
					else if (is_lower_right(i, j)) {
						areas[c - 'A'].x2 = i;
						areas[c - 'A'].y2 = j;
					}
				
					if (is_cutted(i, j))
						possible[c - 'A'] = false;
				}
			}
		}
}

bool scan_inside(int p)
{
	char c = p + 'A';
	int x1 = areas[p].x1, y1 = areas[p].y1, x2 = areas[p].x2, y2 = areas[p].y2;
	for (int i = x1 + 1; i < x2; ++i)
		for (int j = y1 + 1; j < y2; ++j)
			if (ui[i][j] != '.')
				return false;
	return true;
}

void solve()
{
	for (int i = 0; i < 26; ++i)
		if (input[i] && possible[i] && scan_inside(i))
			printf("%c", i + 'A');
	printf("\n");
}

int main()
{
	while (scanf("%d %d", &n, &m) && n != 0 &&& m != 0)
	{
		init();
		find_cutted();
		solve();
	}
	return 0;
}