现在给定一个数组arr,和a,b两个数字,你要做的就是找到(i,j,k)。且满足
1. 0 <= i < j < k < arr.size()
2. |arr[i] - arr[j]| <= a
3. |arr[j] - arr[k]| <= b
统计满足条件的个数并返回(最后结果可能很大,请取1000000007的余数)。
[7,1,8,9,0],3,3
1
只有(7,8,9)符合要求
arr.size() <= 5000其余变量均<=1e9
class Solution: def countTriplets(self , arr , a , b ): # write code here ans = 0 n = len(arr) mod = 10 ** 9 +7 for i in range(n): l,r = 0,0 for j in range(i): if abs(arr[j] - arr[i]) <= a: l += 1 for j in range(i+1, n): if abs(arr[j] - arr[i]) <= b: r += 1 ans = (ans + l*r ) % mod return ans