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LeetCode_665_Easy_BF.js
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LeetCode_665_Easy_BF.js
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/**
* @param {number[]} nums
* @return {boolean}
*/
// Given an array of length n - n >= 1 && <= 10,000
// Array is unsorted.
// Find if the array is sorted in ascending order if we just modify 1 element.
// Complexity: O(n*n) runtime, O(1) space.
var checkPossibility = function(nums) {
// Brute force solution by trying all the possibilities for making a change.
// Best case solution assumes that there is no change required.
// Another possible solution requires that there is only one change.
// One change means that only a single element has to change.
// Only single element that ensures result is making A[i] to A[i-1]
// Making A[i] to -Infinity in case i is 0.
// A BF solution will try making all the possible changes and looking for result.
for (let i=0;i<nums.length;i++) {
const original = nums[i]
nums[i] = i === 0 ? -Infinity : nums[i-1]
if (checkSeqValid(nums)) {
return true
}
nums[i] = original
}
return false
};
// O(n) runtime and O(1) space
function checkSeqValid(nums) {
let last = -Infinity
for (const num of nums) {
if (num < last)
return false
last = num
}
return true
}