[UVa]155:All Squares

利用遞迴找出每一個正方形，然後確定點是否有在此正方形內。
有的話，就加一；
沒有的話，就不用加任何數字。
這樣即可得解。

[C](0.028)

	#include<stdio.h>
	#define SIDE_X_AND_Y 2048
	int squares( int k, int cenx, int ceny, int surx, int sury )
	{
	if( k <= 0 )
	return 0;
	int left = cenx - k;
	int right = cenx + k;
	int top = ceny - k;
	int bottom = ceny + k;
	if( left < 0 || right < 0 || top < 0 || bottom < 0 )
	return 0;
	int result = 0;
	if( surx >= left && surx <= right && sury <= bottom && sury >= top )
	result++;
	result += squares( k/2, left, top, surx, sury );
	result += squares( k/2, right, top, surx, sury );
	result += squares( k/2, left, bottom, surx, sury );
	result += squares( k/2, right, bottom, surx, sury );
	return result;
	}
	int main()
	{
	int k, surx, sury;
	while( scanf( "%d%d%d", &k, &surx, &sury ) != EOF )
	{
	if( k == 0 && surx == 0 && sury == 0 )
	break;
	int cenx = 1024, ceny = 1024;
	printf( "%3d\n", squares( k, cenx, ceny, surx, sury ) );
	}
	return 0;
	}

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