Day111.cpp

// Spiral Order Matrix II

// https://www.interviewbit.com/problems/spiral-order-matrix-ii/

vector<vector<int> > Solution::generateMatrix(int A) {
    
    int n=  A;
    vector<vector<int>> v(n,vector<int> (A, 0));
    int row_start = 0;
    int row_end = n - 1;
    int col_start = 0;
    int col_end = n - 1;
   
   
    int sum = 1;
    while(sum <= n * n) {
        for(int i = col_start; i <= col_end; i++) {
            v[row_start][i] = sum;
            sum += 1;
        }
        
        row_start += 1;
        for(int i = row_start; i <= row_end; i++) {
            v[i][col_end] = sum;
            sum += 1;
        }
        
        col_end -= 1;
        for(int i = col_end; i >= col_start; i--) {
            v[row_end][i] = sum;
            sum += 1;
        }
    
        row_end -= 1;
        for(int i = row_end; i >= row_start; i--) {
            v[i][col_start] = sum;
            sum += 1;
        }
        col_start += 1;
    }
    
    return v;
    
}