add 48

Author: htdwade

48.LongestSubstringWithoutDup/LongestSubstringWithoutDup.cpp

@@ -0,0 +1,41 @@
+/*
+
+剑指Offer
+面试题48：最长不含重复字符的子字符串
+
+题目：请从字符串中找出一个最长的不包含重复字符的子字符串，计算该最长子字符串的长度。
+假设字符串中只包含'a' ~ 'z'的字符。例如，在字符串"arabcacfr"中，最长的不含重复字符的子字符串是"acfr"，
+长度为4。
+
+*/
+
+#include <iostream>
+#include <vector>
+#include <algorithm>
+
+using namespace std;
+
+class Solution {
+public:
+    int longestSubstringWithoutDuplication(string s) {
+        if(s.empty())
+            return 0;
+        vector<int> hash(26, -1);
+        int start = 0;
+        int res = 0;
+        for(int i = 0; i < s.size(); i++){
+            if(hash[s[i] - 'a'] >= start)
+                start = hash[s[i] - 'a'] + 1;
+            hash[s[i] - 'a'] = i;
+            res = max(res, i - start + 1);
+        }
+        return res;
+    }
+};
+
+int main()
+{
+	Solution solution;
+	cout << solution.longestSubstringWithoutDuplication("arabcacfr") << endl;
+	return 0;
+}

README.md

@@ -51,4 +51,5 @@
 |44|[数字序列中某一位的数字](https://www.acwing.com/problem/content/52/)|[C++](https://github.com/htdwade/CodingInterviews/blob/master/44.DigitsInSequence/DigitsInSequence.cpp)|
 |45|[把数组排成最小的数](https://www.nowcoder.com/practice/8fecd3f8ba334add803bf2a06af1b993?tpId=13&tqId=11185&tPage=2&rp=2&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking)|[C++](https://github.com/htdwade/CodingInterviews/blob/master/45.SortArrayForMinNumber/SortArrayForMinNumber.cpp)|
 |46|[把数字翻译成字符串](https://www.acwing.com/problem/content/55/)|[C++](https://github.com/htdwade/CodingInterviews/blob/master/46.TranslateNumbersToStrings/TranslateNumbersToStrings.cpp)|
-|47|[礼物的最大价值](https://www.acwing.com/problem/content/56/)|[C++](https://github.com/htdwade/CodingInterviews/blob/master/47.MaxValueOfGifts/MaxValueOfGifts.cpp)|
+|47|[礼物的最大价值](https://www.acwing.com/problem/content/56/)|[C++](https://github.com/htdwade/CodingInterviews/blob/master/47.MaxValueOfGifts/MaxValueOfGifts.cpp)|
+|48|[最长不含重复字符的子字符串](https://www.acwing.com/problem/content/57/)|[C++](https://github.com/htdwade/CodingInterviews/blob/master/48.LongestSubstringWithoutDup/LongestSubstringWithoutDup.cpp)|