976. Largest Perimeter Triangle

题目链接：https://leetcode.com/problems…Given an array A of positive lengths, return the largest perimeter of a triangle with non-zero area, formed from 3 of these lengths.If it is impossible to form any triangle of non-zero area, return 0.Example 1:Input: [2,1,2]Output: 5Example 2:Input: [1,2,1]Output: 0Example 3:Input: [3,2,3,4]Output: 10Example 4:Input: [3,6,2,3]Output: 8Note:3 <= A.length <= 100001 <= A[i] <= 10^6思路一个面积不为空的三角形，那么必须要最小的两条边之和大于第三边，才能构成一个三角形。并且要周长最大。很容易想到，先对数据进行排序，从最大的开始进行筛选，像窗口一样，往左侧移动，一旦找到符合条件的三角形，就是面积最大的。public int largestPerimeter(int[] A) { Arrays.sort(A); for (int i = A.length - 3; i >= 0; i–) { if (A[i] + A[i + 1] > A[i + 2]) { return A[i] + A[i + 1] + A[i + 2]; } } return 0;}