Spiral Matrix II Solutions in C++

// Source : https://oj.leetcode.com/problems/spiral-matrix-ii/
// Author : Hao Chen
// Date   : 2014-06-30



#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <vector>
using namespace std;

vector<vector<int> > generateMatrix(int n, int m);

vector<vector<int> > generateMatrix(int n) {
    return generateMatrix(n, n);
}

vector<vector<int> > generateMatrix(int n, int m) {
    vector< vector <int> > matrix(n);
    if (n<=0) return matrix;
    for(int i=0; i<n; i++){
        vector<int> v(m);
        matrix[i] = v;
    }

    int row=n, col=m;
    int r, c;
    int cnt=1;
    for (r=0, c=0; r<(row+1)/2 && c<(col+1)/2; r++, c++){
        //top
        for(int i=c; i<col-c; i++){
            matrix[r][i] = cnt++;
        }
        //right
        for(int i=r+1; i<row-r; i++){
            matrix[i][col-c-1] = cnt++;
        }
        //bottom
        for(int i=col-c-2; row-r-1>r && i>=c; i--){
            matrix[row-r-1][i] = cnt++;
        }
        //left
        for(int i=row-r-2; col-c-1>c && i>r; i--){
            matrix[i][c] = cnt++;
        }
        
    }
    return matrix;
}


void printArray(vector<int> v)
{
    cout << "[";
    for(int j=0; j<v.size(); j++) {
        printf(" %02d", v[j]);
    }
    cout << "]" << endl;;
}

void printMatrix(vector< vector<int> > &vv)
{
    for(int i=0; i<vv.size(); i++) {
        printArray(vv[i]);
    }
    cout << endl;
}


int main(int argc, char** argv)
{
    int n=3, m=3;
    if (argc>1){
        m = n = atoi(argv[1]);
    }
    if (argc>2){
        m = atoi(argv[2]);
    }
    vector< vector<int> > matrix = generateMatrix(n, m);
    printMatrix(matrix);
    return 0;
}

#include <vector>
using std::vector;

class Solution {
public:
    vector<vector<int> > generateMatrix(int n) {
        vector<vector<int>> vec(n, vector<int>(n,-1));
        for (int i=0, j=n; value != n*n; ++i, --j)
            spiralFilled(i, j, vec);
        return vec;
    }
private:
    void spiralFilled(int beg, int end, vector<vector<int> >& vec)
    {
        for (int i=beg, j=beg; true; )
        {
            if (vec[i][j] == -1) vec[i][j] = ++value;
            else break;
            if (i == beg && j != end-1) { ++j; continue; }
            if (j == end-1 && i != end-1) { ++i; continue; }
            if (i == end-1 && j != beg) { --j; continue; }
            if (j == beg && i != beg) { --i; continue; }
        }
    }
    
    int value{0};
};

/// Source : https://leetcode.com/problems/spiral-matrix-ii/description/
/// Author : liuyubobobo
/// Time   : 2018-04-24

#include <iostream>
#include <vector>
#include <cmath>

using namespace std;


/// Simulation
/// Time Complexity: O(n^2)
/// Space Complexity: O(1)
class Solution {

private:
    int d[4][2] = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
    int N;

public:
    vector<vector<int>> generateMatrix(int n) {

        if(n == 0)
            return {};

        N = n;
        int maxnum = n * n;

        vector<vector<int>> res(N, vector<int>(N, 0));
        int curx = 0, cury = 0, curd = 0, num = 1;
        while(num <= maxnum){
            if(res[curx][cury] == 0){
                res[curx][cury] = num;
                num ++;
            }

            int nextx = curx + d[curd][0];
            int nexty = cury + d[curd][1];
            if(inArea(nextx, nexty) && res[nextx][nexty] == 0){
                curx = nextx;
                cury = nexty;
            }
            else
                curd = (curd + 1) % 4;
        }

        return res;
    }

private:
    bool inArea(int x, int y){
        return x >= 0 && x < N && y >= 0 && y < N;
    }
};


void print_matrix(const vector<vector<int>>& matrix){
    for(const vector<int>& vec: matrix){
        for(int e: vec)
            cout << e << " ";
        cout << endl;
    }
}

int main() {

    vector<vector<int>> res = Solution().generateMatrix(3);
    print_matrix(res);

    return 0;
}