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88 lines
1.9 KiB
Markdown
Executable File
88 lines
1.9 KiB
Markdown
Executable File
# [970. Powerful Integers](https://leetcode.com/problems/powerful-integers/)
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## 题目
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Given two positive integers `x` and `y`, an integer is *powerful* if it is equal to `x^i + y^j` for some integers `i >= 0` and `j >= 0`.
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Return a list of all *powerful* integers that have value less than or equal to `bound`.
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You may return the answer in any order. In your answer, each value should occur at most once.
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**Example 1**:
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Input: x = 2, y = 3, bound = 10
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Output: [2,3,4,5,7,9,10]
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Explanation:
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2 = 2^0 + 3^0
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3 = 2^1 + 3^0
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4 = 2^0 + 3^1
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5 = 2^1 + 3^1
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7 = 2^2 + 3^1
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9 = 2^3 + 3^0
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10 = 2^0 + 3^2
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**Example 2**:
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Input: x = 3, y = 5, bound = 15
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Output: [2,4,6,8,10,14]
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**Note**:
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- `1 <= x <= 100`
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- `1 <= y <= 100`
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- `0 <= bound <= 10^6`
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## 题目大意
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给定两个正整数 x 和 y，如果某一整数等于 x^i + y^j，其中整数 i >= 0 且 j >= 0，那么我们认为该整数是一个强整数。返回值小于或等于 bound 的所有强整数组成的列表。你可以按任何顺序返回答案。在你的回答中，每个值最多出现一次。
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## 解题思路
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- 简答题，题目要求找出满足 `x^i + y^j ≤ bound` 条件的所有解。题目要求输出中不能重复，所以用 map 来去重。剩下的就是 `n^2` 暴力循环枚举所有解。
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## 代码
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```go
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package leetcode
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import "math"
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func powerfulIntegers(x int, y int, bound int) []int {
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if x == 1 && y == 1 {
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if bound < 2 {
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return []int{}
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}
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return []int{2}
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}
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if x > y {
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x, y = y, x
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}
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visit, result := make(map[int]bool), make([]int, 0)
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for i := 0; ; i++ {
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found := false
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for j := 0; pow(x, i)+pow(y, j) <= bound; j++ {
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v := pow(x, i) + pow(y, j)
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if !visit[v] {
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found = true
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visit[v] = true
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result = append(result, v)
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}
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}
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if !found {
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break
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}
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}
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return result
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}
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func pow(x, i int) int {
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return int(math.Pow(float64(x), float64(i)))
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}
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``` |