LeetCode Spiral Matrix II

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

For example,
Given n = 3,

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

思路：和上一道回旋的类似做法。

class Solution {
public:
    vector<vector<int> > generateMatrix(int n) {
        vector<vector<int> > ans;
        for (int i = 0; i < n; i++) {
            vector<int> t = vector<int>(n, -1);
            ans.push_back(t);
        }

        int dx[4] = {0, 1, 0, -1};
        int dy[4] = {1, 0, -1, 0};
        int dir = 0, x = 0, y = 0;
        for (int i = 1; i <= n*n; i++) {
            ans[x][y] = i;
            if (x+dx[dir] == n || x+dx[dir] < 0 ||
                y+dy[dir] == n || y+dy[dir] < 0 ||
                ans[x+dx[dir]][y+dy[dir]] != -1) {
                    dir = dir == 3 ? 0 : dir + 1;
            }
            x += dx[dir];
            y += dy[dir];
        }

        return ans;
    }
};

LeetCode Spiral Matrix II

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原文地址：http://blog.csdn.net/u011345136/article/details/44514905