Update 0014-longest-common-prefix.cpp

The existing solution was for four sum, I replaced with the actual problem solution

Submission URL: https://leetcode.com/problems/longest-common-prefix/submissions/867645947/

cpp/0014-longest-common-prefix.cpp

@@ -1,59 +1,28 @@
 class Solution {
 public:
- vector<vector<int>> res;
-
- vector<vector<int>> fourSum(vector<int>& nums, int target) {
-
- if(nums.size() < 4) return res;
-
- vector<int>quad;
- sort(nums.begin() , nums.end());
- kSum(0,4,target,nums,quad);
- return res;
- }
-
-
- void kSum (int index , int k , long long target, vector<int> nums , vector<int>&q)
- {
-
- if(k == 2)
- {
- twoSum(index , target, q , nums);
- return;
- }
-
- for(int i = index ; i < nums.size() - k + 1; i++)
- {
- if(i > index && nums[i] == nums[i-1]) continue;
- q.push_back(nums[i]);
- kSum(i+1 , k-1 , target-nums[i] , nums , q);
- q.pop_back();
- } 
-
- }
-
- void twoSum (int start,long long target,vector<int>&ans,vector<int>& nums)
- {
- int lo = start;
- int hi = nums.size()-1;
-
- while(lo < hi)
- {
- int sum = nums[lo]+nums[hi];
- if(sum > target) hi--;
- else if (sum < target) lo++;
-
- else 
- {
- ans.insert(ans.end() , {nums[lo] , nums[hi]});
- res.push_back(ans);
+ string longestCommonPrefix(vector<string>& strs) {
+ string result = strs[0];
+ int charIndex = 0;
 
- ans.pop_back();
- ans.pop_back();
-
- lo++;
- while (lo < hi && nums[lo] == nums[lo - 1]) lo++;
- }
- } 
- }
+ //finding minimum string length - that could be max common prefix
+ long maxCharIndex = strs[0].length();
+ for (int i = 1; i < strs.size(); ++i) {
+ if (strs[i].length() < maxCharIndex) {
+ maxCharIndex = strs[i].length();
+ }
+ }
+
+ while (charIndex < maxCharIndex) {
+ char prevChar = strs[0][charIndex];
+ for (int i = 1; i < strs.size(); ++i) {
+ if (prevChar == strs[i][charIndex]) {
+ continue;
+ }
+ return result.substr(0, charIndex);
+ }
+ ++charIndex;
+ result += prevChar;
+ }
+ return result.substr(0, charIndex);
+ }
 };