【leetcode题解】【有问题，python没AC，java却过了】【M】【66】Perfect Squares

Given a positive integer n, find the least number of perfect square numbers (for example,

1,
4, 9, 16, ...

) which sum to n.

For example, given n =

12

, return

3

because

12
= 4 + 4 + 4

; given n =

13

, return

2

because

13
= 4 + 9

.

Credits:

Special thanks to @jianchao.li.fighter for adding this problem and creating all test cases.

如果一个数x可以表示为一个任意数a加上一个平方数bｘb，也就是x=a+bｘb，那么能组成这个数x最少的平方数个数，就是能组成a最少的平方数个数加上1（因为b*b已经是平方数了）。

不过不知道为何，同样的算法，java，ac了，python，就超时了。

【java的】
public class Solution {
public int numSquares(int n) {
int[] dp = new int[n + 1];
Arrays.fill(dp, Integer.MAX_VALUE);
dp[0] = 0;
for(int i = 1; i <= n; ++i) {
int min = Integer.MAX_VALUE;
int j = 1;
while(i - j*j >= 0) {
min = Math.min(min, dp[i - j*j] + 1);
++j;
}
dp[i] = min;
}
return dp
;
}
}

【python】
class Solution(object):
def numSquares(self, n):
maxx = 9#1<<11
dp = [maxx]*(n+1)
dp[0] = 0
for a in xrange(1,n+1):
b = 1
minn = maxx
while a- b*b >= 0 :
minn = min(dp[a - b*b]+1,minn)
b+=1
dp[a] = minn

return dp