LeetCode_線性表

1、Remove Duplicates from Sorted Array

         Given a sorted array, remove the duplicates in place such that each element appear only once and return the new length.
         Do not allocate extra space for another array, you must do this in place with constant memory.
         For example, Given input array A = [1,1,2],Your function should return length = 2, and A is now [1,2].

class Solution1{
public:
    int removeDuplication(vector<int>&nums){
        int index = 0;
        for (int i = 0; i < nums.size(); i++){
            if (nums[index] != nums[i]){
                nums[++index] = nums[i];
            }
        }
        return index + 1;
    }
};

class Solutions2{
public:
    int removeDuplication(vector<int>&nums){
        return distance(nums.begin(), unique(nums.begin(), nums.end()));
    }
};

class Solutions3{
public:
    int removeDuplication(vector<int>&nums){
        return distance(nums.begin(), removeDuplicates(nums.begin(), nums.end(), nums.begin()));
    }
    template<typename InIt,typename OutIt>
    OutIt removeDuplicates(InIt first, InIt last, OutIt output){
        while (first != last){
            *output++=*first;
            first = upper_bound(first, last, *first);
        }
        return output;
    }
};

總結：

1、distance
2、unique
3、upper_bound

2、Remove Duplicates from Sorted Array II

         Follow up for ”Remove Duplicates”: What if duplicates are allowed at most twice?
         For example, Given sorted array A = [1,1,1,2,2,3],Your function should return length = 5, and A is now [1,1,2,2,3]

class Solution1{
public:
    int removeDuplication(vector<int>&nums){
        if (nums.size() <= 2)
            return nums.size();
        int index = 1;
        for (int i = index+1; i < nums.size(); i++){
            if (nums[index-1] != nums[i]){
                nums[++index] = nums[i];
            }
        }
        return index + 1;
    }
};

class Solution2{
public:
    int removeDuplicates(vector<int>& nums) {
        const int n = nums.size();
        int index = 0;
        for (int i = 0; i < n; ++i) {
            if (i > 0 && i < n - 1 && nums[i] == nums[i - 1] && nums[i] == nums[i + 1])
                continue;
            nums[index++] = nums[i];
        }
        return index;
    }
};