Leetcode 74 Search a 2D Matrix

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:

代码语言：javascript复制

[
  [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

代码语言：javascript复制

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;
    }
};

integer matrix properties row this

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