415:字符串相加

src/main/java/leetcode/editor/cn/AddStrings.java

@@ -0,0 +1,88 @@
+//<p>给定两个字符串形式的非负整数&nbsp;<code>num1</code> 和<code>num2</code>&nbsp;，计算它们的和并同样以字符串形式返回。</p>
+//
+//<p>你不能使用任何內建的用于处理大整数的库（比如 <code>BigInteger</code>），&nbsp;也不能直接将输入的字符串转换为整数形式。</p>
+//
+//<p>&nbsp;</p>
+//
+//<p><strong>示例 1：</strong></p>
+//
+//<pre>
+//<strong>输入：</strong>num1 = "11", num2 = "123"
+//<strong>输出：</strong>"134"
+//</pre>
+//
+//<p><strong>示例 2：</strong></p>
+//
+//<pre>
+//<strong>输入：</strong>num1 = "456", num2 = "77"
+//<strong>输出：</strong>"533"
+//</pre>
+//
+//<p><strong>示例 3：</strong></p>
+//
+//<pre>
+//<strong>输入：</strong>num1 = "0", num2 = "0"
+//<strong>输出：</strong>"0"
+//</pre>
+//
+//<p>&nbsp;</p>
+//
+//<p>&nbsp;</p>
+//
+//<p><strong>提示：</strong></p>
+//
+//<ul>
+//	<li><code>1 &lt;= num1.length, num2.length &lt;= 10<sup>4</sup></code></li>
+//	<li><code>num1</code> 和<code>num2</code> 都只包含数字&nbsp;<code>0-9</code></li>
+//	<li><code>num1</code> 和<code>num2</code> 都不包含任何前导零</li>
+//</ul>
+//<div><div>Related Topics</div><div><li>数学</li><li>字符串</li><li>模拟</li></div></div><br><div><li>👍 541</li><li>👎 0</li></div>
+package leetcode.editor.cn;
+
+/**
+ * Classname ${NAME}
+ * Description 415:字符串相加
+ * Date ${DATE} ${TIME}
+ * author ${USER}
+ */
+public class AddStrings {
+    public static void main(String[] args) {
+        Solution solution = new AddStrings().new Solution();
+        // TO TEST
+    }
+
+    //leetcode submit region begin(Prohibit modification and deletion)
+    class Solution {
+        public String addStrings(String num1, String num2) {
+            StringBuilder str = new StringBuilder();
+            StringBuilder sb1 = new StringBuilder(num1);
+            StringBuilder sb2 = new StringBuilder(num2);
+            sb1.reverse();
+            sb2.reverse();
+            int index = 0;
+            int sum = 0;
+            while (index < sb1.length() || index < sb2.length()) {
+                if (index < sb1.length()) {
+                    sum += (sb1.charAt(index) - '0');
+                }
+                if (index < sb2.length()) {
+                    sum += (sb2.charAt(index) - '0');
+                }
+                if (sum >= 10) {
+                    str.insert(0, (sum % 10));
+                    sum /= 10;
+                } else {
+                    str.insert(0, sum);
+                    sum = 0;
+                }
+                index++;
+            }
+            if (sum > 0) {
+                str.insert(0, sum);
+            }
+            return str.toString();
+        }
+    }
+//leetcode submit region end(Prohibit modification and deletion)
+
+}

src/main/java/leetcode/editor/cn/doc/content/AddStrings.md

@@ -0,0 +1,39 @@
+<p>给定两个字符串形式的非负整数&nbsp;<code>num1</code> 和<code>num2</code>&nbsp;，计算它们的和并同样以字符串形式返回。</p>
+
+<p>你不能使用任何內建的用于处理大整数的库（比如 <code>BigInteger</code>），&nbsp;也不能直接将输入的字符串转换为整数形式。</p>
+
+<p>&nbsp;</p>
+
+<p><strong>示例 1：</strong></p>
+
+<pre>
+<strong>输入：</strong>num1 = "11", num2 = "123"
+<strong>输出：</strong>"134"
+</pre>
+
+<p><strong>示例 2：</strong></p>
+
+<pre>
+<strong>输入：</strong>num1 = "456", num2 = "77"
+<strong>输出：</strong>"533"
+</pre>
+
+<p><strong>示例 3：</strong></p>
+
+<pre>
+<strong>输入：</strong>num1 = "0", num2 = "0"
+<strong>输出：</strong>"0"
+</pre>
+
+<p>&nbsp;</p>
+
+<p>&nbsp;</p>
+
+<p><strong>提示：</strong></p>
+
+<ul>
+	<li><code>1 &lt;= num1.length, num2.length &lt;= 10<sup>4</sup></code></li>
+	<li><code>num1</code> 和<code>num2</code> 都只包含数字&nbsp;<code>0-9</code></li>
+	<li><code>num1</code> 和<code>num2</code> 都不包含任何前导零</li>
+</ul>
+<div><div>Related Topics</div><div><li>数学</li><li>字符串</li><li>模拟</li></div></div><br><div><li>👍 541</li><li>👎 0</li></div>