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Leetcode 2057. Smallest Index With Equal Value

Problem Statement

Given a 0-indexed integer array nums, return the smallest index i of nums such that i mod 10 == nums[i], or -1 if such index does not exist.

Clarifying Questions

  1. What are the constraints on the size of the array?
    • The array size can be from 1 to (10^4).
  2. What are the constraints on the values of the elements in the array?
    • The values of the elements can range from 0 to (10^9).
  3. Do we need to handle any special cases like negative values or non-integer inputs?
    • No, the problem constraints specify non-negative integers.
  4. What should be returned if there are multiple indices satisfying the condition?
    • We return the smallest index.

Strategy

  1. Initialization: We will initialize the result value to be -1, indicating if we don’t find any index that satisfies the condition.

  2. Iterate through the array:
    • We will traverse each index and check if the condition i % 10 == nums[i] holds true.
    • If it does, we return the index immediately because we are looking for the smallest index.
  3. Edge Cases:
    • If the array is empty, though by constraints, it won’t be.
    • If all elements are greater than the index or no index satisfies the condition, return -1.

Code

#include <vector>

class Solution {
public:
    int smallestEqual(std::vector<int>& nums) {
        // Iterate over each index
        for (int i = 0; i < nums.size(); ++i) {
            if (i % 10 == nums[i]) {
                return i;
            }
        }
        // Return -1 if no index satisfies the condition
        return -1;
    }
};

Time Complexity

This solution efficiently checks each index of the array to find the smallest index that meets the given condition.

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