Maximum Length of Pair Chain

Description

You are given n pairs of numbers. In every pair, the first number is always smaller than the second number.

Now, we define a pair (c, d) can follow another pair (a, b) if and only if b < c. Chain of pairs can be formed in this fashion.

Given a set of pairs, find the length longest chain which can be formed. You needn't use up all the given pairs. You can select pairs in any order.

Example 1:

Input: [[1,2], [2,3], [3,4]]
Output: 2
Explanation: The longest chain is [1,2] -> [3,4]

Note:

1. The number of given pairs will be in the range [1, 1000].

Solution(javascript)

/**
 * @param {number[][]} pairs
 * @return {number}
 */
var findLongestChain = function(pairs) {
    pairs.sort((a, b) => a[1]-b[1]);
    let cur = -9007199254740991, ans = 0
    for(let pair of pairs){
        if(pair[0] > cur){
            cur = pair[1];
            ans++;
        }
    }
    return ans;
};