leetcode54順時針打印矩陣
題目鏈接順時針打印矩陣
題目描述:
輸入一個矩陣,按照從外向裏以順時針的順序依次打印出每一個數字。
示例 1:
輸入:matrix = [[1,2,3],[4,5,6],[7,8,9]]
輸出:[1,2,3,6,9,8,7,4,5]
示例 2:
輸入:matrix = [[1,2,3,4],[5,6,7,8],[9,10,11,12]]
輸出:[1,2,3,4,8,12,11,10,9,5,6,7]
限制:
0 <= matrix.length <= 100
0 <= matrix[i].length <= 100
題目分析:按照四個方向遍歷打印即可,控制行數和列數下標的變化,注意越界判斷
代碼:
class Solution {
public int[] spiralOrder(int[][] matrix) {
if(matrix==null||matrix.length==0) return new int[0];
int[] res = new int[(matrix.length*(matrix[0].length))];
int rbegin = 0,rend = matrix.length - 1;
int cbegin = 0,cend = matrix[0].length-1;
int cnt = 0;
while(rbegin<=rend&&cbegin<=cend){
//行不變 列++
for(int i = cbegin;i<=cend;i++){
res[cnt++] = matrix[rbegin][i];
}
rbegin++;
//列不變,行++
for(int i = rbegin;i<=rend;i++){
res[cnt++] = matrix[i][cend];
}
cend--;
//行不變,列--
if(rbegin<=rend){//循環越界判斷
for(int i = cend;i>=cbegin;i--){
res[cnt++] = matrix[rend][i];
}
rend--;
}
//列不變,行--
if(cbegin<=cend){//循環越界判斷
for(int i = rend;i>=rbegin;i--){
res[cnt++] = matrix[i][cbegin];
}
cbegin++;
}
}
return res;
}
}