zoukankan      html  css  js  c++  java
  • 885. Spiral Matrix III

    On a 2 dimensional grid with R rows and C columns, we start at (r0, c0) facing east.

    Here, the north-west corner of the grid is at the first row and column, and the south-east corner of the grid is at the last row and column.

    Now, we walk in a clockwise spiral shape to visit every position in this grid. 

    Whenever we would move outside the boundary of the grid, we continue our walk outside the grid (but may return to the grid boundary later.) 

    Eventually, we reach all R * C spaces of the grid.

    Return a list of coordinates representing the positions of the grid in the order they were visited.

    Example 1:

    Input: R = 1, C = 4, r0 = 0, c0 = 0
    Output: [[0,0],[0,1],[0,2],[0,3]]
    
    
    

    Example 2:

    Input: R = 5, C = 6, r0 = 1, c0 = 4
    Output: [[1,4],[1,5],[2,5],[2,4],[2,3],[1,3],[0,3],[0,4],[0,5],[3,5],[3,4],[3,3],[3,2],[2,2],[1,2],[0,2],[4,5],[4,4],[4,3],[4,2],[4,1],[3,1],[2,1],[1,1],[0,1],[4,0],[3,0],[2,0],[1,0],[0,0]]
    
    
    

    Note:

    1. 1 <= R <= 100
    2. 1 <= C <= 100
    3. 0 <= r0 < R
    4. 0 <= c0 < C

    解法:过程模拟
    class Solution {
    public:
        vector<vector<int>> spiralMatrixIII(int R, int C, int r0, int c0) {
            vector<vector<int>> res;
            int left=c0,right=c0,top=r0,bottom=r0;
            res.push_back({r0,c0});
            int cnt=-1;
            while(left>=0||right<=C-1||top>=0||bottom<=R-1){
                cnt++;
                if(cnt%4==0){
                    right=right+1;
                    if(top<0)
                        continue;
                    for(int j=max(left+1,0);j<=min(right,C-1);j++)
                        res.push_back({top,j});
                }
                if(cnt%4==1){
                    bottom=bottom+1;
                    if(right>C-1)
                        continue;
                    for(int i=max(top+1,0);i<=min(bottom,R-1);i++)
                        res.push_back({i,right});
                }
                if(cnt%4==2){
                    left=left-1;
                    if(bottom>R-1)
                        continue;
                    for(int j=min(right-1,C-1);j>=max(left,0);j--)
                        res.push_back({bottom,j});
    
                }
                if(cnt%4==3) {
                    top=top-1;
                    if(left<0)
                        continue;
                    for (int i = min(bottom-1,R-1); i >= max(top,0); i--)
                        res.push_back({i, left});
    
                }
            }
            return res;
        }
    };
  • 相关阅读:
    JavaScript解析顺序和变量作用域
    JS-BOM
    原生对象-Array
    JavaScript01
    css3动画
    scc的使用
    CSS3学习总结
    Js数组方法大全
    JavaScript判断变量是否为数组
    浏览器兼容性问题及解决方案
  • 原文地址:https://www.cnblogs.com/learning-c/p/9764062.html
Copyright © 2011-2022 走看看