🌕 885. 螺旋矩阵 III

难度: 🌕

• 问题描述
• 解法
• 输出

问题描述

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解法

class Solution {
    int rows;
    int cols;
    public int[][] spiralMatrixIII(int rows, int cols, int rStart, int cStart) {
        // 思路：
        // 从 [rStart, cStart] 点开始
        // 👉 1 👇1 👈 2 👆 2 👉3 👇 3 👈 4 👆 4
        // 找规律
        this.rows = rows;
        this.cols = cols;
        int len = rows * cols;
        int[][] res = new int[len][2];
        int index = 0;
        int i = rStart;
        int j = cStart;
        int step = 1;
        while(index < len) {
            // 向右走 step 步
            for(int m = 0; m < step; m ++) {
                if(isValid(i, j)) {
                    res[index][0] = i;
                    res[index][1] = j;
                    // System.out.println(index + "   aaaa   " + Arrays.toString(res[index]));
                    index ++;
                    if(index == len) 
                        return res;
                }
                j ++;
            }
            
            // 向下走 step 步
            for(int m = 0; m < step; m ++) {
                if(isValid(i, j)) {
                    res[index][0] = i;
                    res[index][1] = j;
                    // System.out.println(index + "   bbbbb   " + Arrays.toString(res[index]));
                    index ++;
                    if(index == len) 
                        return res;
                }
                i ++;
            }
            // 向左走 step + 1 步
            step ++;
            for(int m = 0; m < step; m ++) {
                if(isValid(i, j)) {
                    res[index][0] = i;
                    res[index][1] = j;
                    // System.out.println(index + "   cccc   " + Arrays.toString(res[index]));
                    index ++;
                    if(index == len) 
                        return res;
                }
                j --;
            }
            // 向上走 step + 1 步
            for(int m = 0; m < step; m ++) {
                if(isValid(i, j)) {
                    res[index][0] = i;
                    res[index][1] = j;
                    // System.out.println(index + "   dddd   " + Arrays.toString(res[index]));
                    index ++;
                    if(index == len) 
                        return res;
                }
                i --;
            }
            step ++;
        }
        return res;
    }

    private boolean isValid(int i, int j) {
        if(i < 0 || j < 0) {
            return false;
        }
        if(i >= rows || j >= cols) {
            return false;
        }
        return true;
    }
}

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输出