54. Spiral Matrix

1. Description

Given a matrix of m*n elements, return all elements of the matrix in spiral order.

2. Solution

Just do it. In any loop, print the elements from left to right, top to down, right to left, and down to top.

Repeat the above process, until all elements have been printed.

3. Code

    vector<int> spiralOrder(vector<vector<int>>& matrix) {        vector<int>ans;        int n = matrix.size();        if(n==0) return ans;        int m = matrix[0].size();        int k=0,count = n*m;        int t=0,b=n-1,l=0,r=m-1;        while(k<count){            for(int i = l;i<=r&&k<count;i++){                ans.push_back(matrix[t][i]);                k++;            }            t++;            for(int i=t;i<=b&&k<count;i++){                ans.push_back(matrix[i][r]);                k++;            }            r--;            for(int i=r;i>=l&&k<count;i--){                ans.push_back(matrix[b][i]);                k++;            }            b--;            for(int i = b;i>=t&&k<count;i--){                ans.push_back(matrix[i][l]);                k++;                            }            l++;        }        return ans;    }