LeetCode 240. Search a 2D Matrix II
2017-03-12 21:36
288 查看
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:
Given target =
Given target =
m x n矩阵中,每一行和每一列都是从小到大排列,要求判断一个值是否属于该矩阵。
解决思路:从右上角或从左下角的元素开始搜索。以右上角为例:
如果元素的值等于target,则返回true;
如果元素的值小于target,则应该搜索左边的元素;
如果元素的值大于target,则应当搜索下面的元素;
当左边或者下面没有元素的时候,结束循环,返回false。
代码实现如下:
class Solution {
public:
bool searchMatrix(vector< vector<int> >& matrix, int target) {
if(matrix.size()==0 || matrix[0].size()==0)
return false;
int m=0, n=matrix[0].size()-1;
while(m<matrix.size() && n>=0) {
int x = matrix[m]
;
if(target == x)
return true;
else if(target < x)
--n;
else
++m;
}
return false;
}
};
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.
m x n矩阵中,每一行和每一列都是从小到大排列,要求判断一个值是否属于该矩阵。
解决思路:从右上角或从左下角的元素开始搜索。以右上角为例:
如果元素的值等于target,则返回true;
如果元素的值小于target,则应该搜索左边的元素;
如果元素的值大于target,则应当搜索下面的元素;
当左边或者下面没有元素的时候,结束循环,返回false。
代码实现如下:
class Solution {
public:
bool searchMatrix(vector< vector<int> >& matrix, int target) {
if(matrix.size()==0 || matrix[0].size()==0)
return false;
int m=0, n=matrix[0].size()-1;
while(m<matrix.size() && n>=0) {
int x = matrix[m]
;
if(target == x)
return true;
else if(target < x)
--n;
else
++m;
}
return false;
}
};
相关文章推荐
- Leetcode 240. Search a 2D Matrix II (Medium) (cpp)
- 第十八周:[Leetcode]240. Search a 2D Matrix II
- Leetcode 240. Search a 2D Matrix II[medium]
- leetcode - 240.Search a 2D Matrix II
- LeetCode--240. Search a 2D Matrix II
- LeetCode 240. Search a 2D Matrix II
- Leetcode 240. Search a 2D Matrix II
- LeetCode *** 240. Search a 2D Matrix II
- LeetCode 240. Search a 2D Matrix II
- [leetcode]240. Search a 2D Matrix II
- leetcode240. Search a 2D Matrix II
- Leetcode 240. Search a 2D Matrix II
- LeetCode 240. Search a 2D Matrix II
- 【LeetCode】 240. Search a 2D Matrix II
- leetcode 240. Search a 2D Matrix II
- LeetCode----240. Search a 2D Matrix II (M)
- leetcode 240. Search a 2D Matrix II 模拟
- LeetCode 240. Search a 2D Matrix II
- LeetCode - 240. Search a 2D Matrix II
- LeetCode 240. Search a 2D Matrix II (矩阵内搜索)