59. Spiral Matrix II

題目

Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.

For example,
Given n = 3,
You should return the following matrix:

[
 [ 1, 2, 3 ],
 [ 8, 9, 4 ],
 [ 7, 6, 5 ]
]

           

解析

class Solution_59 {
public:
	vector<vector<int> > generateMatrix(int n) {

		vector<vector<int>> vecs(n, vector<int>(n,1));
		
		int x0 = 0, y0 = 0;
		int x1 = n - 1, y1 = n - 1;

		int index = 0;
		while (x0<=x1&&y0<=y1)
		{
			for (int i = y0; i <= y1;i++)
			{
				vecs[x0][i] = ++index;
			}
			for (int i = x0 + 1; i <= x1;i++)
			{
				vecs[i][y1] = ++index;
			}
			for (int i = y1 - 1; i >= y0;i--)
			{
				vecs[x1][i] = ++index;
			}
			for (int i = x1 - 1; i > x0;i--)
			{
				vecs[i][y0] = ++index;
			}

			x0++, y0++;
			x1--, y1--;
		}
		
		return vecs;
	}
};


           

題目來源

C/C++基本文法學習

STL

C++ primer