leet14：最长公共前缀

最长公共前缀算法解析

最新推荐文章于 2022-09-13 17:07:34 发布

原创最新推荐文章于 2022-09-13 17:07:34 发布 · 142 阅读

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public static String longestCommonPrefix(String[] strs) {
 if(strs ==null||strs.length ==0)return"";
 for(int i = 0; i<strs[0].length(); i++) {
    char c = strs[0].charAt(i);
       for (int j = 1; j < strs.length; j++) {
        if (i == strs[j].length() || strs[j].charAt(i) != c)
            return strs[0].substring(0, i);
    }
}

public static String longestCommonPrefix1(String[] strs) {

    String prefix = strs[0];
    for (int i = 1; i < strs.length; i++)
        while (strs[i].indexOf(prefix) != 0) {
            prefix = prefix.substring(0, prefix.length() - 1);
            if (prefix.isEmpty()) return "";
        }
    return prefix;
}

分治法

public String longestCommonPrefix(String[] strs) {
    if (strs == null || strs.length == 0) return "";
    return longestCommonPrefix(strs, 0 , strs.length - 1);
}

private String longestCommonPrefix(String[] strs, int l, int r) {
    if (l == r) {
        return strs[l];
    }
    else {
        int mid = (l + r)/2;
        String lcpLeft =   longestCommonPrefix(strs, l , mid);
        String lcpRight =  longestCommonPrefix(strs, mid + 1,r);
        return commonPrefix(lcpLeft, lcpRight);
    }
}

String commonPrefix(String left,String right) {
    int min = Math.min(left.length(), right.length());
    for (int i = 0; i < min; i++) {
        if ( left.charAt(i) != right.charAt(i) )
            return left.substring(0, i);
    }
    return left.substring(0, min);
}