Spiral Matrix
Total Accepted: 11102 Total
Submissions: 53832My Submissions
Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.
For example,
Given the following matrix:
[ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9 ] ]
You should return [1,2,3,6,9,8,7,4,5].
注意m、n作为标识量（or 状态量），控制着循环状态转移
class Solution {
public:
vector<int> spiralOrder(vector<vector<int> > &matrix) {
vector<int> res;
int x=-1,y=0;/// @@巧妙设置起点
int n=matrix.size();
if(n==0) return res;
int m=matrix[0].size();
while(m>0&&n>0){
//right
for(int i=0;i<m;i++){
x+=1;
res.push_back(matrix[y][x]);
}
n--;
if(n==0||m==0) break;///@@error:here should have a break condition: n==0 or m==0 all will cause the loop stop
for(int i=0;i<n;i++){
y+=1;
res.push_back(matrix[y][x]);
}
m--;
if(n==0||m==0) break;
for(int i=0;i<m;i++){
x-=1;
res.push_back(matrix[y][x]);
}
n--;
if(n==0||m==0) break;
for(int i=0;i<n;i++){
y-=1;
res.push_back(matrix[y][x]);
}
m--;
if(n==0||m==0) break;
}
return res;
}
};