HackMD
646.Maximum Length of Pair Chain
tags: Medium Array DP Greedy Sorting
646. Maximum Length of Pair Chain
題目描述
You are given an array of n pairs pairs where pairs[i] = [lefti, righti] and lefti < righti.
A pair p2 = [c, d] follows a pair p1 = [a, b] if b < c. A chain of pairs can be formed in this fashion.
Return the length longest chain which can be formed.
You do not need to use up all the given intervals. You can select pairs in any order.
範例
Example 1:
Input: pairs = [[1,2],[2,3],[3,4]]
Output: 2
Explanation: The longest chain is [1,2] -> [3,4].
Example 2:
Input: pairs = [[1,2],[7,8],[4,5]]
Output: 3
Explanation: The longest chain is [1,2] -> [4,5] -> [7,8].
Constraints:
n==pairs.length- 1 <=
n<= 1000 - -1000 <=
lefti<righti<= 1000
解答
C#
public class Solution {
public int FindLongestChain(int[][] pairs) {
// 依區間結尾大小排序
Array.Sort(pairs, (a, b) => a[1].CompareTo(b[1]));
// Greedy 的找出不重疊的區間
int ans = 0;
int maxEnd = int.MinValue;
foreach (var pair in pairs) {
if (pair[0] <= maxEnd) continue;
ans++;
maxEnd = pair[1];
}
return ans;
}
}
JimAug 28, 2023
