标签:ssi targe font ret prope integer ++i cto mis
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.
class Solution {
public:
bool searchMatrix(vector<vector<int>>& matrix, int target) {
int len1 = matrix.size();
if (len1 == 0) return false;
int len2 = matrix[0].size();
if (len2 == 0) return false;
for (int i = 0; i < len1; ++i) {
auto it = lower_bound(matrix[i].begin(), matrix[i].end(), target);
if (it < matrix[i].end() && *it == target) return true;
}
return false;
}
};
Runtime: 88 ms, faster than 23.74% of C++ online submissions for Search a 2D Matrix II.
class Solution {
public:
bool searchMatrix(vector<vector<int>>& matrix, int target) {
int m = matrix.size();
if (m == 0) return false;
int n = matrix[0].size();
int i = 0, j = n - 1;
for (; i < m && j >= 0; ) {
if (matrix[i][j] == target) return true;
else if (matrix[i][j] > target) j--;
else i++;
}
return false;
}
};
Runtime: 52 ms, faster than 55.98% of C++ online submissions for Search a 2D Matrix II.
标签:ssi targe font ret prope integer ++i cto mis
原文地址:https://www.cnblogs.com/ruruozhenhao/p/9900956.html