leetcode
- Map
C++：
class Solution {
public:
int findRepeatNumber(vector<int>& nums) {
std::map<int, int> numberIndexMap;
for ( int i = 0; i < nums.size(); ++i ) {
if ( numberIndexMap.find(nums[i]) != numberIndexMap.end() ) {
return nums[i];
}
numberIndexMap[nums[i]] = i;
}
return 0;
}
};
- 原地哈希法
C++：
class Solution {
public:
int findRepeatNumber(vector<int>& nums) {
for ( int i = 0; i < nums.size(); ++i ) {
while ( nums[i] != i ) {
if ( nums[i] == nums[nums[i]] ) {
return nums[i];
}
while (nums[i] != nums[nums[i]]) {
std::swap(nums[i], nums[nums[i]]);
}
}
}
return 0;
}
};
