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 in ascending from left to right.Integers in each column are sorted in ascending from top to bottom.
For example,
Consider the following matrix:
[ [1, 4, 7, 11, 15], [2, 5, 8, 12, 19], [3, 6, 9, 16, 22], [10, 13, 14, 17, 24], [18, 21, 23, 26, 30] ]Given target = 5, return true.
Given target = 20, return false.
解法一：
从左下角数字开始，--row都比他小，++col都比他大。
class Solution { public: bool searchMatrix(vector<vector<int>>& matrix, int target) { if(matrix.empty()||matrix[0].empty()) return false; if(target < matrix[0][0] || target > matrix.back().back()) return false; int row = matrix.size()-1; int col = 0; while(1){ if(matrix[row][col]<target) ++col; else if (matrix[row][col]>target) --row; else return true; if(row<0 || col>=matrix[0].size()) break; } return false; } };
