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时间限制:1000MS 内存限制:65535K
提交次数:0 通过次数:0
题型: 编程题 语言: G++;GCC
You are given a M*M cloth with some holes on it. Your task is to find a biggest square cloth from it. The following is an example(M=5)
The first line contains the one integer number M (1<= M<=1,000). Then M lines are following. Each line contains M charactors which “.” means cloth and “H” means hole.
The only line of the output contains area of the biggest square cloth mentioned above.
5 H...H ..... ..... .HHH. .....
9
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思路：比较经典的模型了，大白上有几乎一样的原题
#include <cstdio> #include <cstring> #include <algorithm> using namespace std; const int N = 1005; char Map[N][N]; int Up[N][N], Left[N][N], Right[N][N]; int n; void getL() { for(int i = 1; i <= n; ++i) { int lo = 0; for(int j = 1; j <= n; ++j) { if(Map[i][j] == ‘.‘) { Up[i][j] = Up[i - 1][j] + 1; Left[i][j] = max(Left[i - 1][j], lo + 1); }else { Up[i][j] = Left[i][j] = 0; lo = j; } } } } int ans = 0; void getR() { for(int i = 1; i <= n; ++i) { int ro = n + 1; for(int j = n; j >= 1; --j) { if(Map[i][j] == ‘.‘) { Right[i][j] = min(Right[i - 1][j], ro - 1); }else { Right[i][j] = n; ro = j; } ans = max(ans, min(Up[i][j], Right[i][j] - Left[i][j] + 1)); } } } void show(int a[][N]) { for(int i = 1; i <= n; ++i) { for(int j = 1; j <= n; ++j) printf("%d ", a[i][j]); puts(""); } } int main() { while(~scanf("%d", &n)) { for(int i = 1; i <= n; ++i) scanf("%s", Map[i] + 1); for(int i = 0; i <= n; ++i) Up[0][i] = 0; for(int i = 0; i <= n; ++i) Left[0][i] = 0; for(int i = 0; i <= n; ++i) Right[0][i] = n; getL(); getR(); printf("%d\n", ans * ans); } return 0; } /* 5 HH.HH ..... ..... H...H HHHHH */
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原文地址：http://www.cnblogs.com/orchidzjl/p/5072181.html
