Title: Perfect Squares Source: leetcode.com
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.
Java solution
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/* https://leetcode.com/problems/perfect-squares/ */ class PerfectSquares { public static void main(String args[]) { PerfectSquares ps = new PerfectSquares(); System.out.println(ps.numSquares(12)); } public int numSquares(int n) { int[] dp = new int[n+1]; for(int i=1;i<=n;i++) { int min = Integer.MAX_VALUE; for(int j=1;j<=(int)Math.sqrt(i);j++) { min = Math.min(min, dp[i - j*j]+1); } dp[i] = min; } return dp[n]; } } |