Leetcode 7 Solution

This article provides solution to leetcode question 7 (reverse-integer)
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https://leetcode.com/problems/reverse-integer

Thinking Process

Nothing fancy. Just put all the digits into an array, and pop them back reversely.

Time & Space Complexity

Assuming N is the bit-length of the number

  • Time complexity: O(N)
  • Space complexity: O(N)

Solution

class Solution {
public:
    int reverse(int x) {
        vector<int> nums;

        int64_t v = x;

        while (v != 0)
        {
            nums.push_back(v % 10);
            v /= 10;
        }

        for (auto it = nums.begin(); it != nums.end(); it++)
        {
            v = v * 10 + *it;
        }

        if (v > INT_MAX)
            return 0;
        else if (v < INT_MIN)
            return 0;
        else
            return v;
    }
};