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顺时针打印矩阵 java
题目描述
输入一个矩阵,按照从外向里以顺时针的顺序依次打印出每一个数字,例如,如果输入如下4 X 4矩阵: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 则依次打印出数字1,2,3,4,8,12,16,15,14,13,9,5,6,7,11,10.
代码1:
import java.util.ArrayList;
public class Solution {
public ArrayList<Integer> printMatrix(int [][] matrix) {
ArrayList<Integer> al = new ArrayList<>();
int row = matrix.length, col = matrix[0].length;
int left = 0, right = col - 1;
int top = 0, bottom = row - 1;
if(matrix == null){
return null;
}
while(left <= right && top <= bottom){
//从左到右打印
for(int i = left; i <= right; i++){
al.add(matrix[top][i]);
}
//从上到下打印
if(top != bottom){
for(int i = top + 1; i <= bottom; i++){
al.add(matrix[i][right]);
}
}
//从右到左打印
if(top != bottom){
for(int i = right - 1; i >= left; i--){
al.add(matrix[bottom][i]);
}
}
//从下到上打印
if(left != right){
for(int i = bottom - 1; i > top; i--){
al.add(matrix[i][left]);
}
}
left++; right--;
top++; bottom--;
}
return al;
}
}