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2460. Apply Operations to an Array

EasyOpen on LeetCodeProblem statement

Problem Statement

2460. Apply Operations to an Array

Easy

You are given a 0-indexed array nums of size n consisting of non-negative integers.

You need to apply n - 1 operations to this array where, in the ith operation (0-indexed), you will apply the following on the ith element of nums:

After performing all the operations, shift all the 0's to the end of the array.

Return the resulting array.

Note that the operations are applied sequentially, not all at once.

 

Example 1:

Input: nums = [1,2,2,1,1,0]
Output: [1,4,2,0,0,0]
Explanation: We do the following operations:
- i = 0: nums[0] and nums[1] are not equal, so we skip this operation.
- i = 1: nums[1] and nums[2] are equal, we multiply nums[1] by 2 and change nums[2] to 0. The array becomes [1,4,0,1,1,0].
- i = 2: nums[2] and nums[3] are not equal, so we skip this operation.
- i = 3: nums[3] and nums[4] are equal, we multiply nums[3] by 2 and change nums[4] to 0. The array becomes [1,4,0,2,0,0].
- i = 4: nums[4] and nums[5] are equal, we multiply nums[4] by 2 and change nums[5] to 0. The array becomes [1,4,0,2,0,0].
After that, we shift the 0's to the end, which gives the array [1,4,2,0,0,0].

Example 2:

Input: nums = [0,1]
Output: [1,0]
Explanation: No operation can be applied, we just shift the 0 to the end.

 

Constraints:

C++

Source file
class Solution {
public:
    vector<int> applyOperations(vector<int>& nums) {
        int ctZero=0;
        for(int i=0; i<nums.size()-1; i++)
            if(nums[i]==nums[i+1])
                nums[i]*=2, nums[i+1]=0;
        // for(int lt=0,rt=1; max(lt,rt)<nums.size();){
        //     if (nums[lt])   // find 0s
        //         lt++;
        //     while(rt<=lt)
        //         rt++;
        //     if (!nums[rt])  // find non-zeros
        //         rt++;
        //     else swap(nums[lt], nums[rt]);
        // }
        for(int lt=0,rt=0; rt<nums.size();rt++){
            if(nums[rt])
                nums[lt++]=nums[rt];
            else ctZero++;
        }
        int rt=nums.size()-1;
        while(ctZero--)
            nums[rt--]=0;
        return nums;
    }
};