Create 840.cpp

LeetCode-CN/840.cpp

@@ -0,0 +1,66 @@
+class Solution {
+public:
+	int numMagicSquaresInside(vector<vector<int>>& grid) {
+		int rows = grid.size();
+		int cols = grid[0].size();
+
+		int endRow = rows - 3;
+		int endCol = cols - 3;
+
+		int cnt = 0;
+
+		for (int row = 0; row <= endRow; row++)
+		{
+			for (int col = 0; col <= endCol; col++)
+			{
+				int bin[16] = 
+				{ 
+					-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, //0~9
+					0,0,0,0,0,0
+				};
+				for (int i = row; i < row+3; i++)
+				{
+					for (int j = col; j < col + 3; j++)
+					{
+						++bin[grid[i][j]];
+					}
+				}
+				if (find_if(bin + 1, bin + 16, [](const int& x) {return x != 0; }) != (bin + 16)) continue;
+				int base = grid[row][col] + grid[row][col + 1] + grid[row][col + 2];
+
+				bool flag = false;
+
+				for (int i = 0 ; i < 3; i++)
+				{
+					int sum = 0;
+					int xsum = 0;
+					for (int j = 0; j < 3; j++)
+					{
+						sum += grid[row + i][col + j];
+						xsum += grid[row + j][col + i];
+					}
+					if (sum != base || xsum != base)
+					{
+						flag = true;
+						break;
+					}
+				}
+
+				if (flag) continue;
+
+				int dsum = 0;
+				int xdsum = 0;
+				for (int i = 0; i < 3; i++)
+				{
+					dsum += grid[row + i][col + i];
+					xdsum += grid[row + 2 - i][col + 2 - i];
+				}
+				if (dsum != base || xdsum != base) continue;
+
+				++cnt;
+			}
+		}
+
+		return cnt;
+	}
+};