Maximum Length of Pair Chain
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:
The number of given pairs will be in the range [1, 1000].
public class Solution {
// Greedy -> O(NlogN)
// Consider pairs as jobs, with [start time, end time],
// Then the problem is converted to ask the maximum jobs we can accomplish.
public int findLongestChain(int[][] pairs) {
if (pairs == null || pairs.length == 0)
return 0;
Arrays.sort(pairs, (a, b) -> (a[1] - b[1]));
int res = 1, end = pairs[0][1];
for (int i = 1; i < pairs.length; i++) {
if (pairs[i][0] > end) {
res++;
end = pairs[i][1];
}
}
return res;
}
}
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