leetcode
- 标记法
C++：
class Solution {
public:
vector<int> findDisappearedNumbers(vector<int>& nums) {
for ( int i = 0; i < nums.size(); ++i ) {
int number = abs(nums[i]);
int index = number - 1;
if ( nums[index] > 0 ) {
nums[index] *= -1;
}
}
std::vector<int> results;
for ( int i = 0; i < nums.size(); ++i ) {
if ( nums[i] > 0 ) {
results.push_back(i + 1);
}
}
return results;
}
};
- 原地哈希法
C++
class Solution {
public:
vector<int> findDisappearedNumbers(vector<int>& nums) {
for ( int i = 0; i < nums.size(); ++i ) {
while ( nums[i] != nums[nums[i] - 1] ) {
std::swap(nums[i], nums[nums[i] - 1]);
}
}
std::vector<int> results;
for ( int i = 0; i < nums.size(); ++i ) {
if ( nums[i] != i + 1) {
results.push_back(i + 1);
}
}
return results;
}
};
