In-place

tags: LeetCode101,In-place Travel array in reverse order, and record how many times need to swap, which is how many elements not equal val. class Solution { public: int removeElement(vector<int>& nums, int val) { int k = 0; for (int j = nums.size() - 1; j >= 0; --j) { if (nums[j] == val) { for (int i = 0; i < k; ++i) { swap(nums[i + j], nums[j + i + 1]); } } else { k++; } } return k; } };

tags: In-place WikiPedia: https://en.wikipedia.org/wiki/In-place%5Falgorithm Let see two examples before we go further: As above we can see, to reverse a array in-place, we just need swap each two elements in the array from both side to middle. The pseudo code from WikiPedia: function reverse_in_place(a[0..n-1]) for i from 0 to floor((n-2)/2) tmp := a[i] a[i] := a[n − 1 − i] a[n − 1 − i] := tmp The loop travels the array to the middle and swap each other in the list, two points we must be noticed:...

tags: In-place,LeetCode101,In-place Reverse class Solution { public: void reverseString(vector<char>& s) { if (s.size() == 1) { return; } for (int i = 0; i <= (s.size() - 2) / 2; ++i) { swap(s[s.size() - 1 - i], s[i]); } } };