LeetCode Array101
Basic concepts:
An Array is a collection of items. The items could be integers, strings, DVDs, games, books—anything really. The items are stored in neighboring (contiguous) memory locations. Because they’re stored together, checking through the entire collection of items is straightforward.
- Accessing elements in arrays
- Array capacity vs length
Max consecutive ones
Given a binary array
nums, return the maximum number of consecutive1’s in the array.
class Solution:
def findMaxConsecutiveOnes(self, nums: List[int]) -> int:
maxCount = 0
prevMaxCount = 0
for num in nums:
if num:
maxCount += 1
else:
prevMaxCount = max(maxCount, prevMaxCount)
maxCount = 0
return max(prevMaxCount, maxCount)
class Solution {
public:
int findMaxConsecutiveOnes(vector<int>& nums) {
int count = 0;
int maxCount = 0;
for (int num : nums){
if (num) count++;
else {
maxCount = max(maxCount, count);
count = 0;
}
}
return max(maxCount, count);
}
};
Find Numbers with Even Number of Digits
Given an array
numsof integers, return how many of them contain an even number of digits.
class Solution {
public:
int countEven(int num){
int count = 0;
while(true){
if (num >= 10){
num = num/10;
count ++;
}
else {
count ++;
break;
}
}
if (count%2 == 0) return true;
else return false;
}
int findNumbers(vector<int>& nums) {
int count = 0;
for (int num : nums){
if (countEven(num)) count++;
}
return count;
}
};
Squares of a Sorted Array
Given an integer array
numssorted in non-decreasing order, return an array of the squares of each number sorted in non-decreasing order.