61 lines
1.2 KiB
C++
61 lines
1.2 KiB
C++
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/*
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Description: Given a string 's', return the index of the first unique character from the string. If not found, return -1
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Time Complexity: O(n) where n is the length of the string
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*/
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#include <iostream>
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#include <map>
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using namespace std;
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//function starts
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int firstUniqChar(string s)
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{
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//declare a map to store the frequency of the character
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map<char, int> m;
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//storing the character and its frequency in the map for every character in the string
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for (char c : s)
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{
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m[c]++;
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}
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//the frequency of the non-repreating or unique character will be 1
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//1 indicates that it had appeared only once in the string
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//since we want to search from the beginning of the string
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//use for loop from beginning of the string
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//to check if that character appeared for a single time
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//if yes, return the index
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for (int i = 0; i < s.size(); i++)
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{
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if (m[s[i]] == 1)
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{
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return i;
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}
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}
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return -1;
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}
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//main starts
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int main()
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{
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string s;
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cout << "Enter a string: \n";
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getline(cin, s);
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cout << firstUniqChar(s);
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return 0;
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}
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/*
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Example 1:
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Input: s = "leetcode"
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Output: 0
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Example 2:
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Input: s = "loveleetcode"
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Output: 2
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Example 3:
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Input: s = "aabb"
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Output: -1
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*/
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