[LintCode/LeetCode] First Unique Character in a S

Xufc 發布于2019-08-15 13:27 / 3368人閱讀

Problem

Given a string, find the first non-repeating character in it and return it"s index. If it doesn"t exist, return -1.

Example

Given s = "lintcode", return 0.

Given s = "lovelintcode", return 2.

Tags

Amazon Microsoft Bloomberg

Solution

a fast way

class Solution {
    public int firstUniqChar(String s) {
        int[] dict = new int[26];
        for (int i = 0; i < s.length(); i++) {
            dict[s.charAt(i)-"a"]++;
        }
        for (int i = 0; i < s.length(); i++) {
            if (dict[s.charAt(i)-"a"] == 1) return i;
        }
        return -1;
    }
}

a dumb way...

public class Solution {
    public int firstUniqChar(String s) {
        //store string in an array
        char[] str = s.toCharArray();
        //use HashMap to check each character"s frequency
        Map map = new HashMap<>();
        for (int i = 0; i < str.length; i++) {
            char ch = str[i];
            //reset duplicate chars to "#"
            if (map.containsKey(ch)) {
                str[map.get(ch)] = "#";
                str[i] = "#";
            } else {
                map.put(ch, i);
            }
        }
        int index = str.length;
        for (int i = 0; i < str.length; i++) {
            //find the first character that is not "#" and return its index
            if (str[i] != "#") {
                return i;
            }
        }
        //if no unique character, return -1
        return -1;
    }
}

GPU云服務器云服務器 array_unique character unique numeric-character-re

文章版權歸作者所有，未經允許請勿轉載,若此文章存在違規行為，您可以聯系管理員刪除。

轉載請注明本文地址：http://specialneedsforspecialkids.com/yun/68097.html

[LintCode/LeetCode] Unique Paths II

摘要：和完全一樣的做法，只要在初始化首行和首列遇到時置零且即可。對了，數組其它元素遇到也要置零喏，不過就不要啦。 Problem Follow up for Unique Paths: Now consider if some obstacles are added to the grids. How many unique paths would there be? An obstacle...

firim 2019-08-14 15:29 評論0 收藏0
[LintCode/LeetCode] Minimum Window Substring

Problem Given a string source and a string target, find the minimum window in source which will contain all the characters in target. Notice If there is no such window in source that covers all charac...

Corwien 2019-08-14 15:43 評論0 收藏0
[LintCode/LeetCode] 3Sum

摘要：雙指針法的解法。然后用和夾逼找到使三數和為零的三數數列，放入結果數組。對于這三個數，如果循環的下一個數值和當前數值相等，就跳過以避免中有相同的解。 Problem Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplet...

Sunxb 2019-08-14 15:42 評論0 收藏0
[LintCode/LeetCode] Unique Paths

摘要：簡單的動規題目，建立數組。坐標為矩陣的坐標，值為從左上角到這一格的走法總數。賦初值，最上一行和最左列的所有格子的走法都只有一種，其余格子的走法等于其左邊格子走法與上方格子走法之和。最后，返回即可。 Problem A robot is located at the top-left corner of a m x n grid (marked Start in the diagram ...

Gu_Yan 2019-08-14 15:27 評論0 收藏0
[LintCode/LeetCode] Two Strings are Anagrams/Valid

摘要：建立一個長度為的數組，統計所有個字符在出現的次數，然后減去這些字符在中出現的次數。否則，循環結束，說明所有字符在和中出現的次數一致，返回。 Program Write a method anagram(s,t) to decide if two strings are anagrams or not. Example Given s=abcd, t=dcab, return true....

vslam 2019-08-14 15:22 評論0 收藏0