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Write an efficient algorithm that searches for a value in an m x n matrix, return the occurrence of it.
This matrix has the following properties:
Example
Consider the following matrix:
[
[1, 3, 5, 7],
[2, 4, 7, 8],
[3, 5, 9, 10]
]
Given target = 3, return 2.
O(m+n) time and O(1) extra space
做法：
从每一行的最后一个开始比较，如果比target大，则去掉这一列。如果比target小，则去掉这一行。
public class Solution { /** * @param matrix: A list of lists of integers * @param: A number you want to search in the matrix * @return: An integer indicate the occurrence of target in the given matrix */ public int searchMatrix(int[][] matrix, int target) { // write your code here if(matrix==null || matrix.length==0 || matrix[0].length==0) return 0; int count=0; int m=matrix.length; int n=matrix[0].length; int row=0; int col=n-1; while(row<m && col>=0) { if(matrix[row][col]>target) { col--; } else if(matrix[row][col]<target) { row++; } else { count++; row++; col--; } } return count; } }
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原文地址：http://www.cnblogs.com/kittyamin/p/5162021.html
