fd

Author: liwentian

ebook/Backtracking.aux

@@ -11,9 +11,14 @@
 \@writefile{toc}{\contentsline {section}{\numberline {1.2}Wildcard Matching}{2}{section.1.2}}
 \@writefile{toc}{\contentsline {subsubsection}{Description}{2}{section*.3}}
 \@writefile{toc}{\contentsline {subsubsection}{Solution}{2}{section*.4}}
+\@writefile{toc}{\contentsline {section}{\numberline {1.3}Letter Combinations of a Phone Number}{3}{section.1.3}}
+\@writefile{toc}{\contentsline {subsubsection}{Description}{3}{section*.5}}
+\@writefile{lof}{\contentsline {figure}{\numberline {图\nobreakspace 1-1}{ \ignorespaces Phone Keyboard}}{3}{section*.5}}
+\newlabel{fig:phone-keyboard}{{1-1}{3}{Description}{section*.5}{}}
+\@writefile{toc}{\contentsline {subsubsection}{Solution}{3}{section*.6}}
 \FN@pp@footnotehinttrue 
 \@setckpt{Backtracking}{
-\setcounter{page}{3}
+\setcounter{page}{5}
 \setcounter{equation}{0}
 \setcounter{enumi}{0}
 \setcounter{enumii}{0}
@@ -23,20 +28,20 @@
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 \setcounter{part}{0}
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 \setcounter{subsubsection}{0}
 \setcounter{paragraph}{0}
 \setcounter{subparagraph}{0}
-\setcounter{figure}{0}
+\setcounter{figure}{1}
 \setcounter{table}{0}
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+\setcounter{FancyVerbLine}{46}
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-\setcounter{bookmark@seq@number}{3}
+\setcounter{bookmark@seq@number}{4}
 \setcounter{parentequation}{0}
 \setcounter{section@level}{3}
 }

ebook/Backtracking.tex

@@ -92,3 +92,71 @@ \subsubsection{Solution}
 }
 \end{Code}
 
+\newpage
+
+\section{Letter Combinations of a Phone Number}
+
+\subsubsection{Description}
+Given a digit string, return all possible letter combinations that the number could represent.
+
+A mapping of digit to letters (just like on the telephone buttons) is given below.
+
+\begin{center}
+\includegraphics[width=150pt]{phone.png}\\
+\figcaption{Phone Keyboard}\label{fig:phone-keyboard}
+\end{center}
+
+\textbf{Input:} Digit string \code{"23"}
+
+\textbf{Output:} \code{["ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"]}.
+
+\subsubsection{Solution}
+
+\begin{Code}
+private final String[] ARR = {
+        "", "", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"
+};
+
+public List<String> letterCombinations(String digits) {
+    List<String> list = new LinkedList<>();
+    if (!digits.isEmpty()) {
+        helper(digits, 0, list, "");
+    }
+    return list;
+}
+
+private void helper(String digits, int start, List<String> list, String s) {
+    if (start >= digits.length()) {
+        list.add(s);
+        return;
+    }
+    int n = digits.charAt(start) - '0';
+    for (char c : ARR[n].toCharArray()) {
+        helper(digits, start + 1, list, s + c);
+    }
+}
+
+public List<String> letterCombinations2(String digits) {
+    LinkedList<String> queue = new LinkedList<String>();
+    if (digits.length() == 0) {
+        return queue;
+    }
+
+    Queue<String> next = new LinkedList<>();
+    queue.add("");
+
+    for (int i = 0; i < digits.length() && !queue.isEmpty(); ) {
+        String s = queue.poll();
+        int n = digits.charAt(i) - '0';
+        for (char c : ARR[n].toCharArray()) {
+            next.add(s + c);
+        }
+        if (queue.isEmpty()) {
+            queue.addAll(next);
+            next.clear();
+            i++;
+        }
+    }
+    return queue;
+}
+\end{Code}

ebook/images/phone.png

@@ -1,4 +1,4 @@
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+This is XeTeX, Version 3.14159265-2.6-0.99996 (TeX Live 2016) (preloaded format=xelatex 2017.9.4)  5 SEP 2017 11:06
 entering extended mode
  restricted \write18 enabled.
  %&-line parsing enabled.
@@ -1881,7 +1881,32 @@ File: eu1lmtt.fd 2009/10/30 v1.6 Font defs for Latin Modern
 
 
 
-]) [2]
+] [2]
+File: images/phone.png Graphic file (type QTm)
+
+<use  "images/phone.png" >
+\g__fontspec_family_LatinModernMono_int=\count195
+.................................................
+. fontspec info: "no-font-shape"
+. 
+. Could not resolve font Latin Modern Mono/B (it probably doesn't exist).
+.................................................
+.................................................
+. fontspec info: "defining-font"
+. 
+. Font family 'LatinModernMono(0)' created for font 'Latin Modern Mono' with
+. options [].
+. 
+. This font family consists of the following NFSS series/shapes:
+. - 'normal' (m/n) with NFSS spec.: <->"Latin Modern
+. Mono/OT:script=latn;language=DFLT;"
+. - 'small caps'  (m/sc) with NFSS spec.: - 'italic' (m/it) with NFSS spec.:
+. <->"Latin Modern Mono/I/OT:script=latn;language=DFLT;"
+. - 'italic small caps'  (m/itsc) with NFSS spec.: - 'bold italic' (bx/it)
+. with NFSS spec.: <->"Latin Modern Mono/BI/OT:script=latn;language=DFLT;"
+. - 'bold italic small caps'  (bx/itsc) with NFSS spec.: 
+.................................................
+ [3]) [4]
 No file leetcode.ind.
 Package atveryend Info: Empty hook `BeforeClearDocument' on input line 42.
 Package atveryend Info: Empty hook `AfterLastShipout' on input line 42.
@@ -1891,12 +1916,12 @@ Package atveryend Info: Empty hook `AtEndAfterFileList' on input line 42.
 Package atveryend Info: Empty hook `AtVeryVeryEnd' on input line 42.
  ) 
 Here is how much of TeX's memory you used:
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- 550521 string characters out of 6143547
- 566578 words of memory out of 5000000
- 32171 multiletter control sequences out of 15000+600000
- 5028 words of font info for 47 fonts, out of 8000000 for 9000
+ 29160 strings out of 493591
+ 551638 string characters out of 6143547
+ 566615 words of memory out of 5000000
+ 32193 multiletter control sequences out of 15000+600000
+ 5076 words of font info for 53 fonts, out of 8000000 for 9000
  1347 hyphenation exceptions out of 8191
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+ 65i,11n,77p,10414b,588s stack positions out of 5000i,500n,10000p,200000b,80000s
 
-Output written on leetcode.pdf (2 pages).
+Output written on leetcode.pdf (4 pages).

ebook/leetcode.log

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