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Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties:
For example,
Consider the following matrix:
[ [1, 3, 5, 7], [10, 11, 16, 20], [23, 30, 34, 50] ]
这道题还是比较简单的，在一个二维数组查找一个指定元素。可以直接遍历这个数组，不过已经排好序，可以先查找在哪一行，然后在对该行进行二分查找
1 public class Solution { 2 public boolean searchMatrix(int[][] matrix, int target) { 3 boolean foundIndex = false; 4 int index = 0; 5 for(int i = 0; i < matrix.length - 1; i++){ 6 if(matrix[i][0] <= target && matrix[i + 1][0] > target){ 7 foundIndex = true; 8 index = i; 9 break; 10 } 11 }//for 12 if(foundIndex){ 13 return searchByBS(matrix[index], target); 14 } 15 else 16 return searchByBS(matrix[matrix.length - 1], target); 17 } 18 19 /** 20 * 对数组进行二分查找 21 * @param num 22 * @return 23 */ 24 public boolean searchByBS(int num[],int target){ 25 int low = 0; 26 int high = num.length - 1; 27 int middle; 28 while(low <= high){ 29 middle = (low + high) / 2; 30 if(num[middle] == target) 31 return true; 32 else if(num[middle] > target){ 33 high = middle - 1; 34 }else{ 35 low = middle + 1; 36 }//else if 37 }//while 38 return false; 39 } 40 }
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原文地址：http://www.cnblogs.com/luckygxf/p/4216380.html
