Leetcode•Apr 30, 2026
Split Array into Consecutive Subsequences
Hazrat Ali
Leetcode
Determine if it is possible to split nums into one or more subsequences such that both of the following conditions are true:
- Each subsequence is a consecutive increasing sequence (i.e. each integer is exactly one more than the previous integer).
- All subsequences have a length of
3or more.
Return true if you can split nums according to the above conditions, or false otherwise.
A subsequence of an array is a new array that is formed from the original array by deleting some (can be none) of the elements without disturbing the relative positions of the remaining elements. (i.e., [1,3,5] is a subsequence of [1,2,3,4,5] while [1,3,2] is not).
Example 1:
Input: nums = [1,2,3,3,4,5] Output: true Explanation: nums can be split into the following subsequences: [1,2,3,3,4,5] --> 1, 2, 3 [1,2,3,3,4,5] --> 3, 4, 5
Example 2:
Input: nums = [1,2,3,3,4,4,5,5] Output: true Explanation: nums can be split into the following subsequences: [1,2,3,3,4,4,5,5] --> 1, 2, 3, 4, 5 [1,2,3,3,4,4,5,5] --> 3, 4, 5
Example 3:
Input: nums = [1,2,3,4,4,5] Output: false Explanation: It is impossible to split nums into consecutive increasing subsequences of length 3 or more.
Solution
var isPossible = function(nums) {
let freq = new Map();
let need = new Map();
for (let num of nums) {
freq.set(num, (freq.get(num) || 0) + 1);
}
for (let num of nums) {
if (freq.get(num) === 0) continue;
if ((need.get(num) || 0) > 0) {
need.set(num, need.get(num) - 1);
need.set(num + 1, (need.get(num + 1) || 0) + 1);
}
else if ((freq.get(num + 1) || 0) > 0 && (freq.get(num + 2) || 0) > 0) {
freq.set(num + 1, freq.get(num + 1) - 1);
freq.set(num + 2, freq.get(num + 2) - 1);
need.set(num + 3, (need.get(num + 3) || 0) + 1);
}
else {
return false;
}
freq.set(num, freq.get(num) - 1);
}
return true;
};