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  • LeetCode 14. Longest Common Prefix

    https://leetcode.com/problems/longest-common-prefix/description/

    Write a function to find the longest common prefix string amongst an array of strings.

    • Solution里提供了几种方法:横向扫描,纵向扫描,分治,二叉树搜索
    • 我这用的纵向扫描所有字符串,只要找到这些串里第一个不匹配的字符,就找到最长公共前缀
    • 注意此题与最长公共前缀短语的区别(http://www.cnblogs.com/pegasus923/p/5602046.html)
    • 注意之前使用"i > strs[j].size() - 1"代替"i == strs[j].size()",结果出错out of range。因为string.size()是size_t类型,所以size()为0时,"strs[j].size() - 1"会变成"-1 + INTMAX"
    • 注意substr的用法
      • string::substr - C++ Reference
        • http://www.cplusplus.com/reference/string/string/substr/
     1 //
     2 //  main.cpp
     3 //  LeetCode
     4 //
     5 //  Created by Hao on 2017/3/16.
     6 //  Copyright © 2017年 Hao. All rights reserved.
     7 //
     8 
     9 #include <iostream>
    10 #include <cstring>
    11 #include <vector>
    12 using namespace std;
    13 
    14 class Solution {
    15 public:
    16     string longestCommonPrefix(vector<string>& strs) {
    17         // Empty vector
    18         if (strs.empty()) return "";
    19         
    20         // Vertical scanning
    21         for (auto i = 0; i < strs[0].size(); i ++) {
    22             for (auto j = 1; j < strs.size(); j ++) {
    23                 // Find the first string not matched
    24                 // Do not use "i > strs[j].size() - 1" as it's of type size_t, 0 - 1 = INT_MAX rather than -1
    25                 if (i == strs[j].size() || strs[j].at(i) != strs[0].at(i))
    26                     return strs[0].substr(0, i);
    27             }
    28         }
    29         
    30         return strs[0];
    31     }
    32 
    33 };
    34 
    35 int main(int argc, char* argv[])
    36 {
    37     Solution    testSolution;
    38     string      result;
    39     
    40     vector<vector<string>> sVec = {{"abab","aba",""}, {"test a short phrase", "test a slightly longer phrase"}};
    41 
    42     /*
    43      ""
    44      "test a s"
    45      */
    46     for (auto str : sVec) {
    47         result = testSolution.longestCommonPrefix(str);
    48         
    49         cout << result << endl;
    50     }
    51 
    52     return 0;
    53 }
    View Code
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  • 原文地址:https://www.cnblogs.com/pegasus923/p/8034648.html
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