Leetcode 74 Search a 2D Matrix

triplebee

发布于 2018-01-12 15:00:46

4740

发布于 2018-01-12 15:00:46

文章被收录于专栏：计算机视觉与深度学习基础计算机视觉与深度学习基础

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.

在有序矩阵中找目标数字，

二分，中间计算一下x,y坐标

class Solution {
public:
    bool searchMatrix(vector<vector<int>>& matrix, int target) {
        if(matrix.empty()) return false;
        int l=0,r=matrix.size()*matrix[0].size()-1;
        while(l<=r)
        {
            int mid=(l+r)>>1;
            int com=matrix[mid/matrix[0].size()][mid%matrix[0].size()];
            if(com==target) return true;
            if(com<target)
                l=mid+1;
            else
                r=mid-1;
        }
        return false;
    }
};

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原始发表：2016-09-22 ，如有侵权请联系 cloudcommunity@tencent.com 删除

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