URAL 1221 Malevich Strikes Back! (暴力枚举)

#include <stdio.h>
#define MAX_SIZE 101
#define FABS(x) ( (x) > 0 ? (x) : -(x) )

int paper[MAX_SIZE][MAX_SIZE];

int isFigure(int half, int centralRow, int centralColumn){
	int row, column, bound;
	for (row = centralRow - half; row <= centralRow + half; row++){
		//边界先减后增的变换用到了绝对值
		bound = centralColumn - half +  FABS(row - centralRow);
		for (column = centralColumn - half; column < bound; column++)
			if (paper[row][column] == 0)
				return 0;

		bound = centralColumn + half -  FABS(row - centralRow);
		for (column < centralColumn - half +  FABS(row - centralRow); column <= bound; column++)
			if (paper[row][column] == 1)
				return 0;

		for (column = centralColumn + half; column > bound; column--)
			if (paper[row][column] == 0)
				return 0;
	}
	return 1;
}

int main(){
	freopen("input.txt", "r", stdin);
	int paperSize;
	while (scanf("%d", &paperSize) != EOF && paperSize != 0){
		int row, column;
		for (row = 1; row <= paperSize; row++)
			for (column = 1; column <= paperSize; column++)
				scanf("%d", &paper[row][column]);

		//枚举figure的size和中心位置，枚举的思想是多么的重要啊
		int found = 0;
		int figureSize, half, bound, centralRow, centralColumn;
		for (figureSize = paperSize & 1 ? paperSize : paperSize - 1; figureSize >= 3; figureSize -= 2){
			half = figureSize >> 1;
			bound = paperSize - half;
			for (centralRow = half; centralRow <= bound; centralRow++)
				for (centralColumn = half; centralColumn <= bound; centralColumn++)
					if (isFigure(half, centralRow, centralColumn)){
						found = 1;
						goto isFound;
					}
		}
isFound:	
		if (found)
			printf("%d\n", figureSize);
		else
			printf("No solution\n");
	}
	return 0;
}