[LeetCode] 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:

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

Given target = 3, return true.

基础太渣！

 

class Solution {
public:
    bool searchMatrix(vector<vector<int> > &matrix, int target) {
        int h = matrix.size();
        if (h == 0) return false;
        int w = matrix[0].size();
        if (w == 0) return false;
        
        int r = 0, c = w - 1;
        while (r < h && c >= 0) {
            if (matrix[r][c] == target) return true;
            else if (matrix[r][c] > target) c--;
            else r++;
        }
        return false;
    }
};