Contains Duplicate LeetCode in Hindi (Hinglish)

Hindi mein samjho (Hinglish)

Neeche is topic ka Hinglish explanation hai, wahi jo hamare course lesson mein audio narration ke saath chalta hai. Code English mein hai, samjhana Hindi mein.

Contains Duplicate ek one-liner jaisa lagta hai. Isse fool mat hona. Yahin pe tum hash-set reflex wire karte ho: wahi instinct Two Sum, Longest Consecutive Sequence, Group Anagrams, aur har "kya maine yeh value pehle dekhi?" question mein kaam aayega. Isse aise treat karo jaise pehli baar pattern se mil rahe ho.

Problem chhota hai. Ek integer array diya gaya, return karo true agar koi value do ya zyada baar aaye, false agar sab distinct hain. Na indices, na target: bas haan ya na. Constraints ten to the fifth elements tak hain, values minus ten to the ninth se plus ten to the ninth tak, isliye naive approaches large inputs pe time out ho jaayenge.

Pehle pattern pehchano. Jab bhi problem poochhe "kya yeh value pehle se present hai jo maine ab tak dekha?" constant time mein, jawaab hai hash set. Set deta hai O of one average insert aur O of one average lookup. Yahi ek property O of n squared brute force ko ek O of n pass mein collapse kar deti hai.

Brute force se shuru karo taaki optimization earned lage. Do nested loops: har i ke liye, har baad waale j ko scan karo aur check karo values equal hain ya nahi. Outer loop n hai, inner loop bhi n tak, to total O of n squared. n equal ten to the fifth ke liye, yeh ten to the tenth comparisons hain: minutes of CPU time. Bahut slow.

Ab asli unlock. Array left se right walk karte hue, pochhne ke bajaay "kya koi baad waala element iss se match karta hai?", question flip karo. Pochho "kya maine yeh exact value pehle dekhi hai?" Wo "pehle dekha" check fast hona chahiye. Hash set isse O of one bana deta hai. Jaise hi check true lauta, ruk jao aur true return karo: baaki scan karne ki zaroorat nahi.

Yeh hai optimal Python saat lines mein. Set jiska naam "seen" hai, empty se shuru hota hai. Hum har element loop karte hain. Agar element pehle se seen mein hai, turant true return karo. Warna add karo aur continue. Loop bina duplicate mile khatam ho jaaye, to false return karo. Yeh hai pura algorithm.

Chaar edge cases jo interviewer ko pasand hain. Pehla: empty array, false return karo kyunki duplicate karne ko kuch hai hi nahi. Doosra: single element, same reason se false. Teesra: har element same jaise paanch paanch, doosre element pe true return karo. Chautha: extreme integer values jaise ten to the ninth, hash set bina kisi special care ke handle karta hai kyunki Python ints arbitrary precision hain.

Teen approaches, teen complexities. Brute force O of n squared time, O of one space. Sort-then-scan O of n log n time, O of one extra space agar in place sort karo. Hash set O of n time, O of n space. n equal ten to the fifth ke liye, brute force lagbhag sau seconds leta hai; sort lagbhag paanch milliseconds; hash set lagbhag ek millisecond. Hash set time pe jeetta hai memory ki cost pe.

India context. Contains Duplicate ya iske variants TCS NQT, Infosys SP, aur Wipro Elite mein warm-up coding question ke roop mein aate hain. Product companies jaise Flipkart, Razorpay, Swiggy, PhonePe, aur Amazon India isse screening question ya Contains Duplicate Two pochne se pehle stepping stone ki tarah use karte hain. Yahaan stumble kiya to interviewer assume kar lega ki tum Two Sum ya Longest Consecutive Sequence bhi nahi kar sakte.

Python solution

def contains_duplicate(nums):
    seen = set()
    for x in nums:
        if x in seen:
            return True
        seen.add(x)
    return False

Complexity: Brute force (two nested loops): time O(n²), space O(1); Sort, then scan adjacent: time O(n log n), space O(1) extra (in-place sort) or O(n) (Python sorted); Hash set (single pass): time O(n), space O(n).