[leedcode 59] Spiral Matrix II

Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.

For example,
Given n =

3

,

You should return the following matrix:

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

public class Solution {
int res[][];
int val=1;
public int[][] generateMatrix(int n) {
//主要是通过画图，判断每个分支的范围，本题还适应非方阵
res=new int

;
int minRow=0;
int maxRow=n-1;
int minCol=0;
int maxCol=n-1;
int val=1;
while(minRow<=maxRow&&minCol<=maxCol){
generate(minRow,maxRow,minCol,maxCol);
minRow++;
maxRow--;
minCol++;
maxCol--;
}
return res;
}
public void generate(int minRow,int maxRow,int minCol,int maxCol){
for(int i=minCol;i<=maxCol;i++){
res[minRow][i]=val++;
}
for(int i=minRow+1;i<=maxRow;i++){
res[i][maxCol]=val++;
}
for(int i=maxCol-1;i>=minCol;i--){
res[maxRow][i]=val++;
}
for(int i=maxRow-1;i>minRow;i--){
res[i][minCol]=val++;
}

}
}