LeetCode 2784: Check if Array is Good Solution
Master LeetCode problem 2784 (Check if Array is Good), a easy challenge, with our optimized solutions in Java, C++, and Python. Explore detailed explanations, test your code in our interactive editor, and prepare for coding interviews.
2784. Check if Array is Good
Problem Explanation
Explanation
To determine if an array is a good array, we need to check if it is a permutation of an array base where base contains integers from 1 to n-1 exactly once, and n appears twice. We can do this by iterating through the array, counting the frequency of each number, and ensuring that the maximum number is n. Then we check if the count of n is 2 and all other numbers have a count of 1. If these conditions are met, the array is considered good.
- Time complexity: O(n) where n is the length of the input array nums.
- Space complexity: O(n) to store the frequency of each number.
Solution Code
class Solution {
public boolean isGoodArray(int[] nums) {
int n = nums.length;
int[] count = new int[201]; // As per constraints 1 <= num[i] <= 200
for (int num : nums) {
count[num]++;
}
int maxNum = 0;
for (int i = 1; i <= 200; i++) {
if (count[i] > 0) {
if (count[i] > 1 && count[i] != 2) {
return false;
}
maxNum = Math.max(maxNum, i);
}
}
return count[maxNum] == 2 && maxNum == n;
}
}Try It Yourself
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