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[LeetCode]Search a 2D Matrix

时间:2015-08-30 11:15:18      阅读:91      评论:0      收藏:0      [点我收藏+]

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Question :

  •   

    Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties:

     

    • Integers in each row are sorted from left to right.
    • The first integer of each row is greater than the last integer of the previous row.

     

    For example,

    Consider the following matrix:

    [
      [1,   3,  5,  7],
      [10, 11, 16, 20],
      [23, 30, 34, 50]
    ]
    

    Given target = 3, return true.

  • Idea : 
      把matrix視為一維陣列處理。
  • Code:
    bool searchMatrix(int** matrix, int matrixRowSize, int matrixColSize, int target) {
        
        int low = 0, high=matrixRowSize*matrixColSize-1;
        int mid;
        while(low <= high) {
            mid = low + (high - low )/2; // avoid to buffer overflow.
        
            if(matrix[mid/matrixColSize][mid%matrixColSize] < target)
                low = mid + 1; 
            else if(matrix[mid/matrixColSize][mid%matrixColSize] > target)
                high = mid -1;
            else
                return true;
        }
        return false;
    }
    

      

[LeetCode]Search a 2D Matrix

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原文地址:http://www.cnblogs.com/bittorrent/p/4770442.html

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