LeetCode algorithm learning — array — plus one

Hello, everyone. Today, I would like to share with you the next simple difficulty problem of LeetCode [plus one].

Given a non-negative integer represented by a non-empty array of integers, add one to that number.

The highest digit is stored at the beginning of the array, and only a single digit is stored for each element of the array.

You can assume that the integer does not start with zero except the integer 0.

The title

Example 1: Input: digits = [1,2,3] Output: [1,2,4] Explanation: The input array represents the number 123. Example 2: input: digits = [4,3,2,1] output: [4,3,2,2] explanation: the input array represents the number 4321. Example 3: Input: digits = [0] Output: [1]Copy the code

Analysis of the

1. An integer is broken up into an array

2. If an integer is added by 1, it needs to be carried if it ends in 9

solution

1. The iteration

Solution a:The iteration

Train of thought1.Iterate backwards2.modulo3.If I take mod PI0I'm going to keep going1But if you encounter the first position is0, you need to add one digit before the array1* /var plusOne = function (digits) {
  for (let i = digits.length - 1; i >= 0; i--) {
    digits[i] = (digits[i] + 1) % 10;

    if(digits[i] ! = =0) {
      break;
    } else {
      // Add one digit before the array if it is already the first bit
      if (i === 0) {
        digits.unshift(1); }}}return digits;
};

/* The minimum complexity time is O(n), and the maximum complexity is O(1) */ for 2n space

Copy the code

conclusion

This problem examines the application of pairs of arrays to pairs of iterations

You can look at a column I share (front-end algorithm) there are more questions about the algorithm to share, I hope to help you, I will try to keep updated every night, if you like the trouble to help me a like, thank you very much

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