[经典面试题]蛇形矩阵（螺旋矩阵）

【1.打印蛇形矩阵】

Given a matrix ofmxnelements (mrows,ncolumns), return all elements of the matrix in spiral order.

For example,Given the following matrix:

[ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9 ]]

You should return[1,2,3,6,9,8,7,4,5].

【代码】

/**————————————* 日期：2015-02-05* 作者：SJF0115* 题目: 54.Spiral Matrix* 网址：https://oj.leetcode.com/problems/spiral-matrix/* 结果：AC* 来源：LeetCode* 博客：—————————————**/#include <iostream>#include <vector>#include <algorithm>using namespace std;class Solution {public:vector<int> spiralOrder(vector<vector<int> > &matrix) {vector<int> result;if(matrix.empty()){return result;}//ifint row = matrix.size();int col = matrix[0].size();int count = row * col;int index = 1;int beginX = 0,endX = row – 1;int beginY = 0,endY = col – 1;while(index <= count){// rightfor(int i = beginY;i <= endY;++i){result.push_back(matrix[beginX][i]);++index;}//for++beginX;if(beginX > endX){break;}//if// downfor(int i = beginX;i <= endX;++i){result.push_back(matrix[i][endY]);++index;}//for–endY;if(endY < beginY){break;}//if// leftfor(int i = endY;i >= beginY;–i){result.push_back(matrix[endX][i]);++index;}//for–endX;if(endX < beginX){break;}//if// upfor(int i = endX;i >= beginX;–i){result.push_back(matrix[i][beginY]);++index;}++beginY;if(beginX > endY){break;}//if}//whilereturn result;}};int main(){Solution s;vector<vector<int> > matrix = {{1,2,3},{4,5,6},{7,8,9}};vector<int> result = s.spiralOrder(matrix);// 输出for(int i = 0;i < result.size();++i){cout<<result[i]<<" ";}//forcout<<endl;return 0;}

【2.生成蛇形矩阵】

Given an integern, generate a square matrix filled with elements from 1 ton2in spiral order.

For example,Givenn=3,

You should return the following matrix:[ [ 1, 2, 3 ], [ 8, 9, 4 ], [ 7, 6, 5 ]]【代码二】

/**————————————* 日期：2015-02-05* 作者：SJF0115* 题目: 59.Spiral Matrix II* 网址：https://oj.leetcode.com/problems/spiral-matrix-ii/* 结果：AC* 来源：LeetCode* 博客：—————————————**/ class Solution {public:vector<vector<int> > generateMatrix(int n) {vector<vector<int> > matrix(n,vector<int>(n,0));if(n <= 0){return matrix;}//ifint count = n * n;int index = 1;int beginX = 0,endX = n – 1;int beginY = 0,endY = n – 1;while(index <= count){// rightfor(int i = beginY;i <= endY;++i){matrix[beginX][i] = index;++index;}//for++beginX;// downfor(int i = beginX;i <= endX;++i){matrix[i][endY] = index;++index;}//for–endY;// leftfor(int i = endY;i >= beginY;–i){matrix[endX][i] = index;++index;}//for–endX;// upfor(int i = endX;i >= beginX;–i){matrix[i][beginY] = index;++index;}++beginY;}//whilereturn matrix;}};

【代码三】

/**————————————* 日期：2015-02-04* 作者：SJF0115* 题目: 59.Spiral Matrix II* 网址：https://oj.leetcode.com/problems/spiral-matrix-ii/* 结果：AC* 来源：LeetCode* 博客：—————————————**/#include <iostream>#include <vector>#include <algorithm>using namespace std;class Solution {public:vector<vector<int> > generateMatrix(int n) {vector<vector<int> > matrix(n,vector<int>(n,0));if(n <= 0){return matrix;}//ifint count = n * n;int index = 1;int x = 0,y = -1;while(index <= count){// right++y;while(y < n && matrix[x][y] == 0){matrix[x][y++] = index;++index;}//while–y;// down++x;while(x < n && matrix[x][y] == 0){matrix[x++][y] = index;++index;}//while–x;// left–y;while(y >= 0 && matrix[x][y] == 0){matrix[x][y–] = index;++index;}//while++y;// up–x;while(x >= 0 && matrix[x][y] == 0){matrix[x–][y] = index;++index;}//while++x;}//whilereturn matrix;}};int main(){Solution s;int n = 5;vector<vector<int> > matrix = s.generateMatrix(n);// 输出for(int i = 0;i < n;++i){for(int j = 0;j < n;++j){cout<<matrix[i][j]<<" ";}//forcout<<endl;}//forreturn 0;}

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