Press "Enter" to skip to content

Perfect Squares-LeetCode#279

279. 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.

Example 1:

Input: n = 12
Output: 3 
Explanation: 12 = 4 + 4 + 4.

Example 2:

Input: n = 13
Output: 2
Explanation: 13 = 4 + 9.
思路:题目意思为给定一个正整数n,找到总和为n的最小正方数(例如,1,4,9,16 ……)。可以用动态规划的思想,循环里计算,每次增加一个dp数组的长度,里面那个for循环一次循环结束就算好下一个数由几个完全平方数组成,直到增加到第n+1个,返回即可。
代码如下:
public class PerfectSquares {
    public static int numSquares(int n) {
        int[] dp = new int[n + 1];
        Arrays.fill(dp, Integer.MAX_VALUE);
        dp[0] = 0;
        for (int i = 0; i <= n; i++) {
            for (int j = 1; j * j <= i; j++) {
                dp[i] = Math.min(dp[i], dp[i - j * j] + 1);
            }
        }
        return dp[n];
    }
}

Be First to Comment

发表评论

电子邮件地址不会被公开。 必填项已用*标注