Problem:
Write a function to find the longest common prefix string amongst an array of strings.
If there is no common prefix, return an empty string "".
Example 1:
Input: ["flower","flow","flight"]
Output: "fl"
Example 2:
Input: ["dog","racecar","car"]
Output: ""
Explanation: There is no common prefix among the input strings.
Note:
All given inputs are in lowercase letters a-z.
Solution:
ONE
JavaScript specific solution. Get the min len then narrow down the prefix.
/**
* @param {string[]} strs
* @return {string}
*/
let longestCommonPrefix = function (strs) {
if (strs.length > 0) {
let minLen = Math.min(...strs.map((s) => s.length));
const anyStr = strs[0];
while (minLen) {
const prefix = anyStr.slice(0, minLen--);
if (strs.every((s) => s.startsWith(prefix))) {
return prefix;
}
}
}
return "";
};
TWO
/**
* @param {string[]} strs
* @return {string}
*/
let longestCommonPrefix = function (strs) {
if (strs.length <= 0) {
return "";
}
let i = 0;
while (strs.every((s) => s[i] && s[i] === strs[0][i])) {
i++;
}
return strs[0].slice(0, i);
};
THREE
General solution. Build up the prefix.
/**
* @param {string[]} strs
* @return {string}
*/
let longestCommonPrefix = function (strs) {
let prefix = "";
if (strs.length > 0) {
for (let i = 0; ; i++) {
const c = strs[0][i];
if (!c) {
return prefix;
}
for (let j = 0; j < strs.length; j++) {
if (strs[j][i] !== c) {
return prefix;
}
}
prefix += c;
}
}
return prefix;
};
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☆*: .｡. o(≧▽≦)o .｡.:☆☆: .｡. o(≧▽≦)o .｡.:*☆
