Leetcode刷题：螺旋矩阵

并不涉及什么算法

• • 最简单的螺旋矩阵
  • 螺旋矩阵 II
  • 螺旋矩阵 III

54. 螺旋矩阵
剑指 Offer 29. 顺时针打印矩阵
以上两个题目基本相同，但29的测试用例中包含了空矩阵，所以还是要先考虑这种情况。如果矩阵为空，就不能用matrix[0].size()获取矩阵列数。

class Solution {
public:
    vector spiralOrder(vector>& matrix) {

        int m = matrix.size();
        if (m == 0) return {};
        int n = matrix[0].size();
        vector> flag(m, vector(n));
        vector ans(m * n);
        int x = 0, y = 0, i = 0;
        
        while (i < (m * n)) {
            
            while (y < n && !flag[x][y]) {
                ans[i] = matrix[x][y];
                flag[x][y] = true;
                i++, y++;
            }
            y--, x++;

            while (x < m && !flag[x][y]) {
                ans[i] = matrix[x][y];
                flag[x][y] = true;
                i++, x++;
            }
            x--, y--;

            while (y >= 0 && !flag[x][y]) {
                ans[i] = matrix[x][y];
                flag[x][y] = true;
                i++, y--;
            }
            y++, x--;

            while (x >= 0 && !flag[x][y]) {
                ans[i] = matrix[x][y];
                flag[x][y] = true;
                i++, x--;
            }
            x++, y++;

        }
        return ans;
    }
};

59. 螺旋矩阵 II

class Solution {
public:
    vector> generateMatrix(int n) {
        int h = 0, v = 0, x = 0;
        vector> flag(n, vector(n));
        vector> ans(n, vector(n));
        vector num;
        for (int i = 1; i <= n * n; i++) {
            num.push_back(i);
            cout << i;
        }
        while (x < n * n) {
            while (v < n && !flag[h][v]) {
                ans[h][v] = num[x];
                flag[h][v] = true;
                x++, v++;
            }
            v--, h++;
            while (h < n && !flag[h][v]) {
                ans[h][v] = num[x];
                flag[h][v] = true;
                x++, h++;
            }
            h--, v--;
            while (v >= 0 && !flag[h][v]) {
                ans[h][v] = num[x];
                flag[h][v] = true;
                x++, v--;
            }
            v++, h--;
            while (h >= 0 && !flag[h][v]) {
                ans[h][v] = num[x];
                flag[h][v] = true;
                x++, h--;
            }
            h++, v++;
        }
        return ans;

    }
};

class Solution {
public:
    vector> spiralMatrixIII(int rows, int cols, int rStart, int cStart) {
        int step  = 1, cnt = 0;
        vector> ans(rows * cols, vector(1, 2));
        vector> flag(rows, vector(cols));
        while (cnt < rows * cols) {
            for (int j = 0; j < step; j++) {
                if (rStart >= 0 && rStart < rows && cStart >= 0 && cStart < cols) {
                    ans[cnt] = {rStart, cStart};
                    flag[rStart][cStart] = true;
                    cnt++;
                }
                cStart++;
            }

            for (int j = 0; j < step; j++) {
                if (rStart >= 0 && rStart < rows && cStart >= 0 && cStart < cols) {
                    ans[cnt] = {rStart, cStart};
                    flag[rStart][cStart] = true;
                    cnt++;
                }
                rStart++;
            }
            step++;

            for (int j = 0; j < step; j++) {
                if (rStart >= 0 && rStart < rows && cStart >= 0 && cStart < cols) {
                    ans[cnt] = {rStart, cStart};
                    flag[rStart][cStart] = true;
                    cnt++;
                }
                cStart--;
            }
            for (int j = 0; j < step; j++) {
                if (rStart >= 0 && rStart < rows && cStart >= 0 && cStart < cols) {
                    ans[cnt] = {rStart, cStart};
                    flag[rStart][cStart] = true;
                    cnt++;
                }
                rStart--;
            }
            step++;
        }
        return ans;
    }
};