[剑指offer] 29. 顺时针打印矩阵 (for循环条件)

思路：

先定义左上和右下角点坐标，打印可分为从左到右，从上到下，从右到左，从下到上。依次判断最后一圈的四个循环条件。

#include "../stdafx.h"
#include <stdio.h>
#include <stdlib.h>
#include <vector>
#include <iostream>
using namespace std;
 
vector<int> printMatrix(vector<vector<int> > matrix) {
    vector <int> res;
    int row = matrix.size(); // 行数
    int col = matrix[].size();  //列数
    if (row ==  || col == )
        return res;
    int left = , right = col - , top = , bottom = row - ;
    while (left <= right&&top <= bottom){   //循环大条件
        for (int i = left; i <= right; i++)
            res.push_back(matrix[top][i]);
        if (bottom-top >= ){      //从上到下的打印条件
            for (int i = top+; i <= bottom; i++)
                res.push_back(matrix[i][right]);
        }
        if ((bottom - top >=  && (right - left >= ))){  //右到左条件
            for (int i = right- ; i >= left; i--)
                res.push_back(matrix[bottom][i]);
        }
        if ((bottom - top >=  && (right - left >= ))){  //下到上条件，注意for循环里i！=top
            for (int i = bottom - ; i > top; i--)
                res.push_back(matrix[i][left]);
        }
        left++; right--; top++; bottom--;
    }
    return res;
}
 
int main(void){
    vector<vector<int>> array = { { , , ,  }, { , , ,  }, { , , ,  }, {,,,} };
    vector<int>vec = printMatrix(array);
 
    vector <int>:: iterator it;
    for (it = vec.begin(); it != vec.end();it++)
        cout << *it << endl;
 
    getchar();
    return ;
}