[LeetCode] Spiral Matrix II

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 ]
]

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Array

思路：在Spiral Matrix的基础上进行修改，还是dfs

class Solution {enum direct{RIGHT = 0, DOWN, LEFT, UP};vector<int> m_res;vector<vector<int> > m_matrix;vector<vector<bool> > m_valid;int m_cnt;public:void dfs(int i, int j, enum direct d)  {   int row = m_matrix.size();int col = m_matrix[0].size();//cout << i <<",\t" << j << endl;m_cnt++;m_matrix[i][j] = m_cnt;m_valid[i][j] = false;if(d == RIGHT){if( j <= col-2 && m_valid[i][j+1])dfs(i, j+1, RIGHT);else if(i <= row-2 && m_valid[i+1][j])dfs(i+1, j, DOWN);}else if(d == DOWN){if(i <= row-2 && m_valid[i+1][j])dfs(i+1, j, DOWN);else if(j >= 1 && m_valid[i][j-1])dfs(i, j-1, LEFT);}else if(d == LEFT){if(j >= 1 && m_valid[i][j-1] )dfs(i, j-1, LEFT);else if(i >= 1 && m_valid[i-1][j])dfs(i-1, j, UP);}else if(d == UP){if(i >= 1 && m_valid[i-1][j])dfs(i-1, j, UP);else if(j <= col-1 && m_valid[i][j+1])dfs(i, j+1, RIGHT );}}
public:vector<vector<int> > generateMatrix(int n){if(n == 0)return m_matrix;// construct the matrixvector<int> row(n, 0);m_matrix.resize(n, row);//for(int i = 0; i < n; i++)//    m_matrix.push_back(row);
vector<bool> valid(n, true);m_valid.resize(n, valid);//for(int i = 0; i < n; i++)//    m_valid.push_back(valid);
m_cnt = 0;dfs(0, 0, RIGHT);return m_matrix;}
};

转载于:https://www.cnblogs.com/diegodu/p/4318326.html

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