方法一：两次二分查找
cpp
class Solution {
public:
bool searchMatrix(vector<vector<int>> matrix, int target) {
auto row = upper_bound(matrix.begin(), matrix.end(), target, [](const int b, const vector<int> &a) {
return b < a[0];
});
if (row == matrix.begin()) {
return false;
}
--row;
return binary_search(row->begin(), row->end(), target);
}
};方法二：一次二分查找
cpp
class Solution {
public:
bool searchMatrix(vector<vector<int>>& matrix, int target) {
int m = matrix.size(), n = matrix[0].size();
int low = 0, high = m * n - 1;
while (low <= high) {
int mid = (high - low) / 2 + low;
int x = matrix[mid / n][mid % n];
if (x < target) {
low = mid + 1;
} else if (x > target) {
high = mid - 1;
} else {
return true;
}
}
return false;
}
};