剑指OFFER——顺时针打印矩阵

输入一个矩阵，按照从外向里以顺时针的顺序依次打印出每一个数字，例如，如果输入如下矩阵： 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 则依次打印出数字1,2,3,4,8,12,16,15,14,13,9,5,6,7,11,10.

class Solution {
public:
    vector<int> printMatrix(vector<vector<int> > matrix) {
        int row = matrix.size();
        int col = matrix[0].size();
        vector<int> res;
         
        // 输入的二维数组非法，返回空的数组
        if (row == 0 || col == 0)  return res;
         
        // 定义四个关键变量，表示左上和右下的打印范围
        int left = 0, top = 0, right = col - 1, bottom = row - 1;
        while (left <= right && top <= bottom)
        {
            // left to right
            for (int i = left; i <= right; ++i)  res.push_back(matrix[top][i]);
            // top to bottom
            for (int i = top + 1; i <= bottom; ++i)  res.push_back(matrix[i][right]);
            // right to left
            if (top != bottom)
            for (int i = right - 1; i >= left; --i)  res.push_back(matrix[bottom][i]);
            // bottom to top
            if (left != right)
            for (int i = bottom - 1; i > top; --i)  res.push_back(matrix[i][left]);
            left++,top++,right--,bottom--;
        }
        return res;
    }
};

#include <iostream>
#include <vector>
using namespace std;

void PrintMatrix(vector <vector<int>>& vec) {
    int row = vec.size();
    int col = vec[0].size();
    int start = 0;
    int num = 0;
    while (start*2 < col && start*2 < row) {
        int endx = col - start - 1;
        int endy = row - start - 1;

        for (int i = start; i <=endx; i++)
            vec[start][i] = ++num;
        if (start < endy) {
            for (int i = start + 1; i <= endy; i++)
                vec[i][endx] = ++num;
        }
        if (start < endx&&start < endy) {
            for (int i = endx-1; i >= start; i--)
                vec[endy][i] = ++num;
        }

        if (start < endx&&start < endy - 1) {
            for (int i = endy - 1; i > start; i--)
                vec[i][start] = ++num;

        }
        start++;
    }
    return;
}
int main() {
    int num;
    cin >> num;
    vector<vector<int>> vec1(num, vector<int>(num, 0));
    PrintMatrix(vec1);
    for (int i = 0; i < num; i++)
        for (int j = 0; j < num; j++)
            cout<< vec1[i][j]<<" ";
    return 0;
}

来源：https://www.cnblogs.com/LUO77/p/5403330.html

标签

vector

num

top

matrix