633:平方数之和

LeetCode/src/main/java/leetcode/editor/cn/SumOfSquareNumbers.java

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+//给定一个非负整数 c ，你要判断是否存在两个整数 a 和 b，使得 a2 + b2 = c 。 
+//
+// 
+//
+// 示例 1： 
+//
+// 输入：c = 5
+//输出：true
+//解释：1 * 1 + 2 * 2 = 5
+// 
+//
+// 示例 2： 
+//
+// 输入：c = 3
+//输出：false
+// 
+//
+// 示例 3： 
+//
+// 输入：c = 4
+//输出：true
+// 
+//
+// 示例 4： 
+//
+// 输入：c = 2
+//输出：true
+// 
+//
+// 示例 5： 
+//
+// 输入：c = 1
+//输出：true 
+//
+// 
+//
+// 提示： 
+//
+// 
+// 0 <= c <= 231 - 1 
+// 
+// Related Topics 数学 
+// 👍 195 👎 0
+
+package leetcode.editor.cn;
+
+//633:平方数之和
+public class SumOfSquareNumbers {
+    public static void main(String[] args) {
+        //测试代码
+        Solution solution = new SumOfSquareNumbers().new Solution();
+        //true
+        System.out.println(solution.judgeSquareSum(5));
+        //false
+        System.out.println(solution.judgeSquareSum(3));
+        //true
+        System.out.println(solution.judgeSquareSum(4));
+        //true
+        System.out.println(solution.judgeSquareSum(2));
+        //true
+        System.out.println(solution.judgeSquareSum(1));
+    }
+
+    //力扣代码
+    //leetcode submit region begin(Prohibit modification and deletion)
+    class Solution {
+        public boolean judgeSquareSum(int c) {
+            int num = (int) Math.sqrt(c);
+            int i = num;
+            while (i >= Math.sqrt(c - num * num)) {
+                if (c == i * i) {
+                    return true;
+                }
+                int num1 = (int) Math.sqrt(c - i * i);
+                if (i * i + num1 * num1 == c) {
+                    return true;
+                }
+                i--;
+            }
+            return false;
+//            // 官方
+//            for (long a = 0; a * a <= c; a++) {
+//                double b = Math.sqrt(c - a * a);
+//                if (b == (int) b) {
+//                    return true;
+//                }
+//            }
+//            return false;
+        }
+    }
+//leetcode submit region end(Prohibit modification and deletion)
+
+}

LeetCode/src/main/java/leetcode/editor/cn/SumOfSquareNumbers.md

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+<p>给定一个非负整数&nbsp;<code>c</code>&nbsp;，你要判断是否存在两个整数 <code>a</code> 和 <code>b</code>，使得&nbsp;<code>a<sup>2</sup> + b<sup>2</sup> = c</code> 。</p>
+
+<p>&nbsp;</p>
+
+<p><strong>示例 1：</strong></p>
+
+<pre><strong>输入：</strong>c = 5
+<strong>输出：</strong>true
+<strong>解释：</strong>1 * 1 + 2 * 2 = 5
+</pre>
+
+<p><strong>示例 2：</strong></p>
+
+<pre><strong>输入：</strong>c = 3
+<strong>输出：</strong>false
+</pre>
+
+<p><strong>示例 3：</strong></p>
+
+<pre><strong>输入：</strong>c = 4
+<strong>输出：</strong>true
+</pre>
+
+<p><strong>示例 4：</strong></p>
+
+<pre><strong>输入：</strong>c = 2
+<strong>输出：</strong>true
+</pre>
+
+<p><strong>示例 5：</strong></p>
+
+<pre><strong>输入：</strong>c = 1
+<strong>输出：</strong>true</pre>
+
+<p>&nbsp;</p>
+
+<p><strong>提示：</strong></p>
+
+<ul>
+	<li><code>0 &lt;= c &lt;= 2<sup>31</sup> - 1</code></li>
+</ul>
+<div><div>Related Topics</div><div><li>数学</li></div></div>\n<div><li>👍 195</li><li>👎 0</li></div>