387. First Unique Character in a String
Given a string, find the first non-repeating character in it and return it‘s index. If it doesn‘t exist, return -1.
Examples:
s = "leetcode" return 0. s = "loveleetcode", return 2.
Note: You may assume the string contain only lowercase letters.
package leetcode.easy;
public class FirstUniqueCharacterInAString {
public int firstUniqChar(String s) {
java.util.HashMap<Character, Integer> count = new java.util.HashMap<Character, Integer>();
int n = s.length();
// build hash map : character and how often it appears
for (int i = 0; i < n; i++) {
char c = s.charAt(i);
count.put(c, count.getOrDefault(c, 0) + 1);
}
// find the index
for (int i = 0; i < n; i++) {
if (count.get(s.charAt(i)) == 1)
return i;
}
return -1;
}
@org.junit.Test
public void test() {
System.out.println(firstUniqChar("leetcode"));
System.out.println(firstUniqChar("loveleetcode"));
}
}
LeetCode_387. First Unique Character in a String
原文：https://www.cnblogs.com/denggelin/p/11875310.html