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# 970. 强整数 - Powerful Integers

给定两个非负整数 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。



### Example:

输入：x = 2, y = 3, bound = 10

2 = 2^0 + 3^0
3 = 2^1 + 3^0
4 = 2^0 + 3^1
5 = 2^1 + 3^1
7 = 2^2 + 3^1
9 = 2^3 + 3^0
10 = 2^0 + 3^2


输入：x = 3, y = 5, bound = 15



## Solutions

### Solution 【BF】 ( 22ms)

class Solution {
public List<Integer> powerfulIntegers(int x, int y, int bound) {
boolean[] nums = new boolean[bound+1];
for (int i = 0; i <=  bound; i++) {
if(Math.pow(x, i)>bound)
break;
for (int j = 0; j < bound; j++) {
if(Math.pow(x, i) + Math.pow(y, j)>bound)
break;
nums[(int)(Math.pow(x, i) + Math.pow(y, j))] = true;
}
}
for (int i = 1; i < nums.length; i++) {
if(nums[i])
}
return result;
}
}


### Solution  ( 5ms)

class Solution {
public List<Integer> powerfulIntegers(int x, int y, int bound) {
List<Integer> list  = new ArrayList<Integer>();
if (x==1&&y==1)
{
if(2<=bound)
return list;
}
if(x==1||y==1){
int t =0;
while(Math.pow(x,t) + Math.pow(y,t)<=bound){
t++;
}
return list;
}
for(int i =0 ; Math.pow(x,i)<bound;i++){
for(int j= 0;Math.pow(y,j)<bound;j++){
int temp = (int)(Math.pow(x,i) + Math.pow(y,j));
if(temp<=bound && !list.contains(temp))
}
}
return list;
}
}