[leetcode 54] Spiral Matrix

Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.

Example 1:

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

Example 2:

Input: [ [1, 2, 3, 4], [5, 6, 7, 8], [9,10,11,12] ] Output: [1,2,3,4,8,12,11,10,9,5,6,7]

 

 

문제 풀이:
구현문제 - 아래 그림대로 구현한다.

맨 위 row와 오른쪽 col을 돌고 아래 row와 왼쪽 col를 돈다.

class Solution {
public:
    vector<int> spiralOrder(vector<vector<int>>& matrix) {
        vector<int> answer;
        
        int n = matrix.size();
       
        
        if(n==0){
            return answer;
        }
        
        int r1=0, r2=n-1;
        
        int m = matrix[0].size();
        if(m == 0){
            for(int i=0; i<n; i++){
                answer.push_back(matrix[n][0]);
            }
            
            return answer;
        }
        
        int c1=0, c2=m-1;
        
        while(r1<=r2 && c1<=c2){
            for(int c = c1; c<=c2; c++)
                answer.push_back(matrix[r1][c]);
            
            for(int r = r1+1; r<=r2; r++)
                answer.push_back(matrix[r][c2]);
            
            if(r1 < r2 && c1 < c2){
                for(int c = c2-1; c>c1; c--)
                    answer.push_back(matrix[r2][c]);
                
                for(int r = r2; r>r1; r--)
                    answer.push_back(matrix[r][c1]);
            }
            
            r1++;
            r2--;
            c1++;
            c2--;
        }
        
        return answer;
    }
};