g0001_0100.s0015_3sum.Solution.cpp Maven / Gradle / Ivy

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104 LeetCode algorithm problem solutions

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// #Medium #Top_100_Liked_Questions #Top_Interview_Questions #Array #Sorting #Two_Pointers
// #Data_Structure_II_Day_1_Array #Algorithm_II_Day_3_Two_Pointers #Udemy_Two_Pointers
// #Big_O_Time_O(n*log(n))_Space_O(n^2) #2024_05_22_Time_53_ms_(90.17%)_Space_27.2_MB_(64.08%)

#include 
using namespace std;

class Solution {
public:
    vector> threeSum(vector& nums) {
        sort(nums.begin(), nums.end());
        int n = nums.size();
        vector> result;
        for (int i = 0; i < n - 2; i++) {
            if (i > 0 && nums[i] == nums[i - 1]) continue;
            int left = i + 1;
            int right = n - 1;
            while (left < right) {
                int sum = nums[i] + nums[left] + nums[right];
                if (sum == 0) {
                    result.push_back({nums[i], nums[left], nums[right]});
                    while (left < right && nums[left] == nums[left + 1]) left++;
                    while (left < right && nums[right] == nums[right - 1]) right--;
                    left++;
                    right--;
                } else if (sum < 0) {
                    left++;
                } else {
                    right--;
                }
            }
        }
        return result;
    }
};