LeetCode:279. Perfect Squares(完美的平方)
阿新 • • 發佈:2018-12-21
Given a positive integer n, find the least number of perfect square numbers (for example, 1, 4, 9, 16, ...
) which sum to n.
Example 1:
Input: n = 12
Output: 3
Explanation: 12 = 4 + 4 + 4.
Example 2:
Input: n = 13
Output: 2
Explanation: 13 = 4 + 9.
方法1:動態規劃
int[] dp = new int[n+1]; dp[0] = 0; for (int i = 1; i <= n; i++) { int min = Integer.MAX_VALUE; for (int k = 1; k * k <= i; k++) { min = Math.min(min, 1+dp[i-k*k]); } dp[i] = min; } return dp[n];
時間複雜度:O(n^2)
空間複雜度:O(n)