0528-random-pick-with-weight.adoc

528. Random Pick with Weight

{leetcode}/problems/random-pick-with-weight/[LeetCode - Random Pick with Weight^]

Given an array w of positive integers, where w[i] describes the weight of index i, write a function pickIndex which randomly picks an index in proportion to its weight.

Note:

1. 1 <= w.length <= 10000

2. 1 <= w[i] <= 10^5

3. pickIndex will be called at most 10000 times.

Example 1:

Input:
 ["Solution","pickIndex"]
 [[[1]],[]]
Output: [null,0]

Example 2:

Input:
 ["Solution","pickIndex","pickIndex","pickIndex","pickIndex","pickIndex"]
 [[[1,3]],[],[],[],[],[]]
Output: [null,0,1,1,1,0]

Explanation of Input Syntax:

The input is two lists: the subroutines called and their arguments. Solution’s constructor has one argument, the array `w. pickIndex has no arguments. Arguments are always wrapped with a list, even if there aren’t any.

思路分析

前缀和+二分查找

一刷

link:{sourcedir}/_0528_RandomPickWithWeight.java[role=include]

参考资料

1. 528. 按权重随机选择 - 官方题解

2. 528. 按权重随机选择 - 【宫水三叶】一题双解 :「前缀和 + 二分」&「模拟（桶轮询）」