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.
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.
解题一：暴力解法
/**
* @param {number[][]} matrix
* @param {number} target
* @return {boolean}
*/
var searchMatrix = function(matrix, target) {
// 暴力解法
for (let i = 0; i < matrix.length; i++) {
for (let j = 0; j < matrix[0].length; j++) {
if (matrix[i][j] == target) {
return true;
}
}
}
return false;
};解题二：二分法
/**
* @param {number[][]} matrix
* @param {number} target
* @return {boolean}
*/
var searchMatrix = function(matrix, target) {
if(!matrix || matrix.length < 1 || matrix[0].length < 1) {
return false
}
let col = matrix[0].length-1;
let row = 0;
while(col >= 0 && row <= matrix.length-1) {
if(target == matrix[row][col]) {
return true;
} else if(target < matrix[row][col]) {
col --
} else if(target > matrix[row][col]) {
row ++
}
}
return false;
};