Given an array consists of non-negative integers, your task is to count the number of triplets chosen from the array that can make triangles if we take them as side lengths of a triangle. Example 1: Input: [2,2,3,4] Output: 3 Explanation: Valid combinations are: 2,3,4 (using the first 2) 2,3,4 (using the second 2) 2,2,3
Assume a is the longest edge, b and c are shorter ones, to form a triangle, they need to satisfy len(b) + len(c) > len(a).
L:
这是return numbers, return value 刚简单， 首先sort ,然后遍历，看当前值+ 前值> 后值
public class Solution {
public int triangleNumber(int[] nums) {
int result = 0;
if (nums.length < 3) return result;
Arrays.sort(nums);
for (int i = 2; i < nums.length; i++) {
int left = 0, right = i - 1;
while (left < right) {
if (nums[left] + nums[right] > nums[i]) {
result += (right - left);
right--;
}
else {
left++;
}
}
}
return result;
}
}
