LeetCode646. Maximum Length of Pair Chain

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本文探讨了如何解决最长数对链问题，这是一种常见的算法挑战。通过对给定数对进行排序并采用特定策略来确定最长可能的数对链，文章提供了一个简洁高效的解决方案。示例演示了输入为[[1,2],[2,3],[3,4]]时，最长链长度为2。

646. Maximum Length of Pair Chain

题目：

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]

题目分析：非常简单的一道题，但是题目说的是动态规划，但是我并没有用动态规划去做。

代码：

bool cmp(vector<int> a, vector<int> b) {
    if (a[0] < b[0]) return true;
    else if (a[0] == b[0]) return a[1] <= b[1];
    else return false;
}

class Solution {
public:
    int findLongestChain(vector<vector<int>>& pairs) {
        if (pairs.empty()) return 0;
        sort(pairs.begin(), pairs.end(), cmp);
        int res = 1, tmp1 = pairs[0][0], tmp2 = pairs[0][1];
        for (int i = 1; i < pairs.size(); i++) {
            if (pairs[i][0] > tmp2) {
                res++;
                tmp2 = pairs[i][1];
            }
            tmp2 = min(pairs[i][1], tmp2);
        }
        return res;
    }
};