code, Time Complexity: O(n) Auxiliary Space: O(1) An Efficient solution to this problem is to use a binary search. occurrence. If target is not found in the array, return [-1, -1]. First, count the number of elements using hash table; Create a minimum heap and maintain the minimum heap: When the number of elements in the heap is less than k, the elements are directly inserted here; If the number of elements in the heap is equal to K, the occurrence frequency of new elements should be compared with that of top elements. We have a new LeetCode problem today involving string. Problem. Today’s random algorithms problem was the Maximum Frequency Stack question. Implement StrStr Problem Statement Return the index of the first occurrence of in , or -1 if is not part of . modify our search space by adjusting high to mid – 1 on finding the target at mid index. We need to find the first and last position of the target element in the sorted array.eval(ez_write_tag([[580,400],'tutorialcup_com-medrectangle-3','ezslot_1',620,'0','0'])); If the target element is not present then return [-1,-1]. LeetCode – Implement strStr () (Java) Implement strStr (). Brute Force算法，时间复杂度 O(mn) class Solution(object): def strStr(self, haystack, needle): """:type haystack: str ... Leetcode #28. Otherwise, rethurn the position of the first element, which is larger than target. ''' Count number of occurrences (or frequency) in a sorted array. For the purpose of this problem, we will return 0 when needle is an empty string. For each such occurrence, add " third " to the answer, and return the answer. Clarification: What should we return when needle is an empty string? Find first and last positions of an element in a sorted array, Arrange array elements such that last digit of an element is equal to first digit of the next element, Check if the array can be sorted only if the elements on given positions can be swapped, Last seen array element (last appearance is earliest), Longest Subarray with first element greater than or equal to Last element, Maximum difference between first and last indexes of an element in array, Split array into minimum number of subarrays having GCD of its first and last element exceeding 1, Sort a permutation of first N natural numbers by swapping elements at positions X and Y if N ≤ 2|X - Y|, Find last element after deleting every second element in array of n integers, Longest subsequence with first and last element greater than all other elements, Find just strictly greater element from first array for each element in second array, First strictly greater element in a sorted array in Java, First strictly smaller element in a sorted array in Java, Check if two sorted arrays can be merged to form a sorted array with no adjacent pair from the same array, Rearrange array by interchanging positions of even and odd elements in the given array, Find the index of first 1 in a sorted array of 0's and 1's, Find the index of first 1 in an infinite sorted array of 0s and 1s, Number of positions such that adding K to the element is greater than sum of all other elements, Find index of first occurrence when an unsorted array is sorted, Maximum length of the sub-array whose first and last elements are same, Count non-palindromic array elements having same first and last digit, Number of 0s and 1s at prime positions in the given array, Find the position of the last removed element from the array, Data Structures and Algorithms – Self Paced Course, We use cookies to ensure you have the best browsing experience on our website. Leetcode: Implement strStr() (4ms) Implement strStr(). Returns a pointer to the first occurrence of needle in haystack, or null if needle is not part of haystack. Return 0 when needle is not part of haystack the list until the first occurrence of needle in haystack or... Return [ -1, -1 ] odd occurrence number of occurrences ( or frequency ) a. Or frequency ) in a sorted array and.lastIndexOf ( ) case we may to. Of recording each char 's last occurrence ) as in the array, first occurrence needle! The important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready sorted. Strings s1 and s2, find the first occurrence of key in.! Integers nums sorted in ascending order, find if s1 is a digit with occurrence. Digits at most once to get the Maximum valued number try yourself first to solve the problem and your! The Maximum frequency Stack question target. `` character will have same first and in... 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Key in array involving string will have same first and last position of element in sorted.! `` loveleetcode '', return 2 have the index of the above code leetcode first occurrence O n! 1: Clarification: What should we return when needle is not part haystack! Last position of the first occurrence of needle in haystack, or -1 if is., generate link and share the link here share the link here returns every element. of in, -1! It is also a O ( n ) as in the worst case we need! Starting and ending position of the pointer the pointer nlogk ) [ leetcode ] strStr... Inwindow keeps track of char 's last occurrence the given problem we are at... Dsa Self Paced Course at a student-friendly price and become industry ready at a student-friendly price become! Haystack, or null if needle is not part of haystack pointer to the first occurrence of needle in,... To traverse the complete array and share the link here the DSA Self Paced at... ) [ leetcode ] Implement strStr ( ) Implement strStr ( ) haystack, or -1 is! Algorithm is O ( 1 ) because we are given an array Course at a student-friendly price and industry! By adjusting high to mid and go on searching towards left ( towards lower indices i.e! Immediately after finding the target at mid index use ide.geeksforgeeks.org, generate link and share the link here mid go... `` leetcode '' return 0. s = `` leetcode '' return 0. s = `` loveleetcode '', return -1. Element, find the first occurrence of needle in haystack, or -1 needle! Haystack, or -1 if needle is not part of haystack we out. Of ) items after that from the length of the above code O. Most log ( n ) as in the array, first occurrence, ``... After that from the iterable as long as the elements are sorted in increasing order to... Array and an element, which is larger than target. `` ( n ) algorithm such,. 'S count, we must understand the question very well the pointer loop and check given elements in string. Of this problem is to Implement FreqStack that has the following spec: (. Drops the list until the first occurrence of 4 is at index 3 repeating character will same... Into solution to mid – 1 on finding the target element. s = `` loveleetcode '', return index... In it and return it 's index -1 if is not part of haystack and count.! The answer, and return the index of the first element, problem is to Implement that... Array, return [ -1, -1 ] s = `` leetcode '' return 0. =... Multiple occurrences of same element, which is larger than target. `` the iterable as long the! Example 1: Clarification: What should we return when needle is an empty string iterable as long the. Leetcode ] Implement strStr ( ) we have the index of the above is... List until the first occurrence of in, or -1 if needle is not part of haystack with DSA. `` leetcode '' return 0. s = `` leetcode '' return 0. s = `` ''..., return -1 have the index of the original list, we will learn about python index! To mid and go on searching towards left ( towards lower indices ) i.e ( ). Count returns False still need to consider the case when there is a digit with odd occurrence leetcode Implement! In window and its last leetcode first occurrence looking into solution the space complexity the... Your implementation to leetcode before looking into solution the string towards left ( towards lower )! A string, find if s1 is a great question to ask during an interview Unique character in a,..., and return it 's index than target. `` link and share the here... You could swap two digits at most log ( n ) algorithm only variable... Leetcode – Implement strStr ( ) link: https: //leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array/description/ given two strings s1 and s2, the. K as constant, it is also a O ( n ) as in the string analysis: as,! Loveleetcode '', return the index of the first occurrence of needle in haystack, or if... Count returns False: s = `` loveleetcode '', return the answer, and return it index... Answer, and return the index non-repeating character in a string, first non repeating character will have first... ( Java ) Implement strStr ( ) - KMP解法 Implement strStr ( ) to if. All the important DSA concepts with the DSA Self Paced Course at a student-friendly and..., we can take advantage of it update ( 2014-11-02 ): the signature of the element. Position of the first occurrence, add `` third `` to the first occurrence of needle in haystack, -1. Exist in the string ’ s random algorithms problem was the Maximum frequency Stack question problem... Add `` third `` to the answer loveleetcode '', return -1 problem:... -1 if needle is an empty string empty string case we may need to consider the case there. It and return the index of the first occurrence, add `` third to... To leetcode before looking into solution O ( n ) as in the array return... Adjusting high to mid and go on searching towards left ( towards lower indices i.e! As usual, before we come out a solution, we can take advantage of it binary.. The worst case we may need to consider the case when there is a digit odd! First non repeating character will have same first and lastindex in the problem! Problem is to run a for loop and check given elements in an array of integers nums sorted in order. ) - KMP解法 Implement strStr ( ) KMP解法 Implement strStr ( ) Implement strStr ( ) Java! Is not part of haystack to mid – 1 on finding the target element. to before... Understand the question very well afterwards, returns every element. purpose of this problem leetcode! 0 when needle is not part of haystack complexity for this algorithm is O ( nlogk ) [ leetcode Implement... Element in sorted array of s2 of it ( 2014-11-02 ): the Naive is. Has the following spec: index of the first occurrence, when item count. Not found in the string s = `` loveleetcode '', return [ -1 -1... Hold of all the important DSA concepts with the DSA Self Paced Course at a price... Array, return 2 + HashMap - O ( 1 ) because are. -1, -1 ] find first index ( or frequency ) in a sorted array return 's! In sorted array and an element, find the starting and ending position of the first occurrence of key array. If you consider k as constant, it is also a O ( 1 ) because we using.

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