[LeetCode]Longest Common Prefix

最新推荐文章于 2017-12-06 18:33:50 发布

原创最新推荐文章于 2017-12-06 18:33:50 发布 · 2k 阅读

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本文介绍了一种寻找字符串数组中最长公共前缀的有效算法。通过选取最短字符串作为基准，逐个字符比较来确定所有字符串的公共部分。该方法简单且高效，适用于多种编程任务。

class Solution {
//1. find out the minimum size string as the pivot string
//2. check every other string and update the minSize
public:
    string longestCommonPrefix(vector<string> &strs) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if(strs.size() == 0) return string("");
		int minSize = strs[0].size();
		int pivotIdx = 0;
		for(int i = 0; i < strs.size(); ++i)
			if(strs[i].size() < minSize)
			{
				minSize = strs[i].size();
				pivotIdx = i;
			}

		for(int i = 0; i < strs.size(); ++i)
		{
			if(i == pivotIdx) continue;
			for(int j = 0; j < minSize; ++j)
			{
				if(strs[i][j] != strs[pivotIdx][j])
				{
					minSize = j;
					break;
				}
			}
		}
		return strs[pivotIdx].substr(0, minSize);
    }
};

second time

class Solution {
public:
    string longestCommonPrefix(vector<string> &strs) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if(strs.size() == 0) return string("");
        
        int strIdx = 0;
        //choose the smallest string first
        for(int i = 1; i < strs.size(); ++i)
            if(strs[i].size() < strs[strIdx].size()) strIdx = i;

        int commonLen = strs[strIdx].size();
        for(int i = 0; i < strs.size(); ++i)
        {
            if(i == strIdx) continue;
            int curLen = 0;
            for(int j = 0; j < strs[i].size() && j < commonLen; ++j)
            {
                if(strs[strIdx][j] == strs[i][j]) curLen++;
                else break;
            }
            commonLen = curLen;
        }
        
        return strs[strIdx].substr(0, commonLen);
    }
};