【劍指offer】面試題 29. 順時針打印矩陣
阿新 • • 發佈:2018-05-12
如果 clas for 輸入 offer ID amp 代碼實現 AR
面試題 29. 順時針打印矩陣
題目描述
題目: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,例如,如果輸入如下矩陣: 1 2 3 4 5 6 7 8 9 10
11 12 13 14 15 16 則依次打印出數字1,2,3,4,8,12,16,15,14,13,9,5,6,7,11,10.
解答過程
下圖的矩陣順時針打印結果為:1, 2, 3, 4, 8, 12, 16, 15, 14, 13, 9, 5, 6, 7, 11, 10
代碼實現
import java.util.ArrayList; public class Solution { public ArrayList<Integer> printMatrix(int [][] matrix) { ArrayList<Integer> res = new ArrayList<Integer>(); if (matrix.length == 0) { return res; } int rowBegin = 0; int rowEnd = matrix.length-1; int colBegin = 0; int colEnd = matrix[0].length - 1; while (rowBegin <= rowEnd && colBegin <= colEnd) { // Traverse Right for (int j = colBegin; j <= colEnd; j ++) { res.add(matrix[rowBegin][j]); } rowBegin++; // Traverse Down for (int j = rowBegin; j <= rowEnd; j ++) { res.add(matrix[j][colEnd]); } colEnd--; if (rowBegin <= rowEnd) { // Traverse Left for (int j = colEnd; j >= colBegin; j --) { res.add(matrix[rowEnd][j]); } } rowEnd--; if (colBegin <= colEnd) { // Traver Up for (int j = rowEnd; j >= rowBegin; j --) { res.add(matrix[j][colBegin]); } } colBegin ++; } return res; } }
【劍指offer】面試題 29. 順時針打印矩陣