1081:不同字符的最小子序列

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

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+//返回 s 字典序最小的子序列，该子序列包含 s 的所有不同字符，且只包含一次。 
+//
+// 注意：该题与 316 https://leetcode.com/problems/remove-duplicate-letters/ 相同 
+//
+// 
+//
+// 示例 1： 
+//
+// 
+//输入：s = "bcabc"
+//输出："abc"
+// 
+//
+// 示例 2： 
+//
+// 
+//输入：s = "cbacdcbc"
+//输出："acdb" 
+//
+// 
+//
+// 提示： 
+//
+// 
+// 1 <= s.length <= 1000 
+// s 由小写英文字母组成 
+// 
+// Related Topics 栈 贪心算法 字符串 
+// 👍 95 👎 0
+
+package leetcode.editor.cn;
+
+import java.util.Stack;
+
+//1081:不同字符的最小子序列
+public class SmallestSubsequenceOfDistinctCharacters {
+    public static void main(String[] args) {
+        //测试代码
+        Solution solution = new SmallestSubsequenceOfDistinctCharacters().new Solution();
+    }
+
+    //力扣代码
+    //leetcode submit region begin(Prohibit modification and deletion)
+    class Solution {
+        public String smallestSubsequence(String s) {
+            boolean[] isHave = new boolean[26];
+            int[] count = new int[26];
+            for (int i = 0; i < s.length(); i++) {
+                count[s.charAt(i) - 'a']++;
+            }
+            Stack<Character> stack = new Stack<>();
+            for (int i = 0; i < s.length(); i++) {
+                char ch = s.charAt(i);
+                if (!isHave[ch - 'a']) {
+                    while (!stack.isEmpty() && stack.peek() > ch) {
+                        if (count[stack.peek() - 'a'] <= 0) {
+                            break;
+                        }
+                        isHave[stack.peek() - 'a'] = false;
+                        stack.pop();
+                    }
+                    isHave[ch - 'a'] = true;
+                    stack.push(ch);
+                }
+                count[ch - 'a']--;
+            }
+            StringBuilder str = new StringBuilder();
+            while (!stack.isEmpty()) {
+                str.insert(0, stack.pop());
+            }
+            return str.toString();
+            //官网
+//            boolean[] vis = new boolean[26];
+//            int[] num = new int[26];
+//            for (int i = 0; i < s.length(); i++) {
+//                num[s.charAt(i) - 'a']++;
+//            }
+//
+//            StringBuilder sb = new StringBuilder();
+//            for (int i = 0; i < s.length(); i++) {
+//                char ch = s.charAt(i);
+//                if (!vis[ch - 'a']) {
+//                    while (sb.length() > 0 && sb.charAt(sb.length() - 1) > ch) {
+//                        if (num[sb.charAt(sb.length() - 1) - 'a'] > 0) {
+//                            vis[sb.charAt(sb.length() - 1) - 'a'] = false;
+//                            sb.deleteCharAt(sb.length() - 1);
+//                        } else {
+//                            break;
+//                        }
+//                    }
+//                    vis[ch - 'a'] = true;
+//                    sb.append(ch);
+//                }
+//                num[ch - 'a']--;
+//            }
+//            return sb.toString();
+        }
+    }
+//leetcode submit region end(Prohibit modification and deletion)
+
+}

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

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+<p>返回 <code>s</code> 字典序最小的子序列，该子序列包含 <code>s</code> 的所有不同字符，且只包含一次。</p>
+
+<p><strong>注意：</strong>该题与 316 <a href="https://leetcode.com/problems/remove-duplicate-letters/">https://leetcode.com/problems/remove-duplicate-letters/</a> 相同</p>
+
+<p> </p>
+
+<p><strong>示例 1：</strong></p>
+
+<pre>
+<strong>输入：</strong><code>s = "bcabc"</code>
+<strong>输出<code>：</code></strong><code>"abc"</code>
+</pre>
+
+<p><strong>示例 2：</strong></p>
+
+<pre>
+<strong>输入：</strong><code>s = "cbacdcbc"</code>
+<strong>输出：</strong><code>"acdb"</code></pre>
+
+<p> </p>
+
+<p><strong>提示：</strong></p>
+
+<ul>
+	<li><code>1 <= s.length <= 1000</code></li>
+	<li><code>s</code> 由小写英文字母组成</li>
+</ul>
+<div><div>Related Topics</div><div><li>栈</li><li>贪心算法</li><li>字符串</li></div></div>\n<div><li>👍 95</li><li>👎 0</li></div>