Spiral Matrix Problem Solution

Spiral Matrix Problem: Given an m x n matrix, return all elements of the matrix in spiral order.

Input: matrix = [[1,2,3],[4,5,6],[7,8,9]]
Output: [1,2,3,6,9,8,7,4,5]

Spiral Matrix Problem Solution

Problem Solution In Python

def spiralOrder(self, matrix: List[List[int]]) -> List[int]:
        res = []
        r1, r2 = 0, len(matrix) - 1
        c1, c2 = 0, len(matrix[0]) - 1
        
        while r1 <= r2 and c1 <= c2:
            for c in range(c1, c2 + 1):
                res.append(matrix[r1][c])
            for r in range(r1 + 1, r2 + 1):
                res.append(matrix[r][c2])
            if r1 < r2 and c1 < c2:
                for c in range(c2 - 1, c1, -1):
                    res.append(matrix[r2][c])
                for r in range(r2, r1, -1):
                    res.append(matrix[r][c1])
            
            r1 += 1; r2 -= 1
            c1 += 1; c2 -= 1
        
        return res

Problem Solution In Java

public class Solution {
public List<Integer> spiralOrder(int[][] matrix) {
    List<Integer> list = new ArrayList<Integer>();
    if(matrix == null || matrix.length == 0 || matrix[0].length == 0) return list;
    int row = matrix.length;
    int col = matrix[0].length;
    int left = 0, right = col-1;
    int top = 0, bottom = row-1;
    while(true){
        for(int i = left; i<=right; i++){
            list.add(matrix[top][i]);
        }
        top++;
        if(top > bottom) break;
        for(int i = top; i<=bottom; i++){
            list.add(matrix[i][right]);
        }
        right--;
        if(right < left) break;
        for(int i = right; i>=left; i--){
            list.add(matrix[bottom][i]);
        }
        bottom--;
        if(bottom < top) break;
        for(int i = bottom; i>=top; i--){
            list.add(matrix[i][left]);
        }
        left++;
        if(left > right) break;
    }
    return list;
}
}

Problem Solution In C++

class Solution {
    public:
        vector<int> spiralOrder(vector<vector<int>>& matrix) {
            int i = 0, m = matrix.size(), n = m == 0 ? 0 : matrix[0].size(), num = 0, mi = min(m,n);
            vector<int> answer;
            while( num < m*n && mi-2*i >= 0) {
                answer.insert(answer.end(), matrix[i].begin() + i, matrix[i].end() - i );
                for( int k = i + 1; k < m-i ; k++ ) answer.push_back(matrix[k][n-i-1]);
                if( m - i - 1 > i ) answer.insert(answer.end(), matrix[m-i-1].rbegin() + i + 1, matrix[m-i-1].rend() - i );
                for( int k = m-i-2; k >= i+1 && n-i-1>i; k-- ) answer.push_back(matrix[k][i]);
                num+= (2*(m-2*i) + 2*(n-2*i) - 4); i++;
            }
            return answer;
        }
};

Problem Solution In C

int* spiralOrder(int** m, int matrixRowSize, int* matrixColSize, int* ret_size){
    if(matrixRowSize==0){
        *ret_size=0;
        return NULL;
    } 

    int col=*matrixColSize;
    int rows=matrixRowSize;

    int start_row=0;   int end_row=rows-1; 
    int start_col=0;   int end_col=col-1;

    *ret_size=rows*col;

    int* ret_arr=(int*)malloc((*ret_size)*sizeof(int));
    int ret_i=0;

    while(ret_i<(rows*col)){
        for(int i=start_col;i<=end_col;i++){
            ret_arr[ret_i++]=m[start_row][i];   
        }
        start_row++;
        if(ret_i==(rows*col)) break; //These stmts are required when R!=C (rectangular matrices)
        for(int i=start_row;i<=end_row;i++){
            ret_arr[ret_i++]=m[i][end_col]; 
        }
        end_col--;
        if(ret_i==(rows*col)) break;
        for(int i=end_col;i>=start_col;i--){
            ret_arr[ret_i++]=m[end_row][i];     
        }
        end_row--;
        if(ret_i==(rows*col)) break;
        for(int i=end_row;i>=start_row;i--){
            ret_arr[ret_i++]=m[i][start_col];   
        }
        start_col++;
        if(ret_i==(rows*col)) break;
    }
    return ret_arr;
    
    
}