Shortest distance to every other character from given character

Given a string S and a character X where , for some . The task is to return an array of distances representing the shortest distance from the character X to every other character in the string.

Examples:

Input: S = “geeksforgeeks”, X = ‘e’
Output: [1, 0, 0, 1, 2, 3, 3, 2, 1, 0, 0, 1, 2]
for S = ‘g’ nearest ‘e’ is at distance = 1 i.e. S = ‘e’.
similarly, for S = ‘e’, distance = 0.
for S = ‘o’, distance = 3 since we have S = ‘e’, and so on.

Input: S = “helloworld”, X = ‘o’
Output: [4, 3, 2, 1, 0, 1, 0, 1, 2, 3]

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach: For each character at index i in S[], let us try to find the distance to the next character X going left to right, and from right to left. The answer will be the minimum of these two values.

• When going from left to right, we remember the index of the last character X we’ve seen. Then the answer is i – prev.
• When going from right to left, the answer is prev – i.
• We take the minimum of these two answers to create our final distance array.
• Finally, print the array.

Below is the implementation of above approach:

C++

 // C++ implementation of above approach  #include    using namespace std;    // Function to return required  // array of distances  void shortestDistance(string S, char X) {         // Find distance from occurrences of X      // appearing before current character.      int prev = INT_MIN;     vector ans;            for (int i = 0; i < S.length(); i++)     {          if (S[i] == X)              prev = i;          ans.push_back(i - prev);     }        // Find distance from occurrences of X      // appearing after current character and      // compare this distance with earlier.      prev = INT_MAX;      for (int i = S.length() - 1; i >= 0; i--)     {          if (S[i] == X)              prev = i;                        ans[i] = min(ans[i], prev - i);      }        for (auto val: ans)         cout << val << ' '; }    // Driver code  int main() {     string S = "geeksforgeeks";     char X = 'g';     shortestDistance(S, X);      return 0; }    // This code is contributed by Rituraj Jain

Java

 // Java implementation of above approach  import java.util.*;    class GFG {    // Function to return required  // array of distances  static void shortestDistance(String S, char X)  {         // Find distance from occurrences of X      // appearing before current character.      int prev = Integer.MAX_VALUE;      Vector ans = new Vector<>();             for (int i = 0; i < S.length(); i++)      {          if (S.charAt(i) == X)              prev = i;          ans.add(i - prev);      }         // Find distance from occurrences of X      // appearing after current character and      // compare this distance with earlier.      prev = Integer.MAX_VALUE;     for (int i = S.length() - 1; i >= 0; i--)      {          if (S.charAt(i) == X)              prev = i;                         ans.set(i, Math.min(ans.get(i), prev - i));      }         for (Integer val: ans)              System.out.print(val+" "); }     // Driver code  public static void main(String[] args) {     String S = "geeksforgeeks";      char X = 'g';      shortestDistance(S, X); } }    // This code is contributed by Rajput-Ji

Python3

 # Python3 implementation of above approach    # Function to return required  # array of distances def shortestDistance(S, X):        # Find distance from occurrences of X     # appearing before current character.     prev = float('-inf')     ans = []     for i, j in enumerate(S):         if j == X:             prev = i         ans.append(i - prev)           # Find distance from occurrences of X     # appearing after current character and     # compare this distance with earlier.     prev = float('inf')     for i in range(len(S) - 1, -1, -1):         if S[i] == X:             prev = i         ans[i] = min(ans[i], prev - i)        # return array of distance     return ans       # Driver code S = "geeksforgeeks" X = "g"    # Function call to print answer print(shortestDistance(S, X))

C#

 // C# implementation of above approach using System; using System.Collections.Generic;    class GFG {            // Function to return required      // array of distances     public static void shortestDistance(String S, char X){                    // Find distance from occurrences of X          // appearing before current character.          int prev = int.MaxValue;         List ans = new List();         for (int i=0; i=0; i--)         {             if (S[i] == X)                 prev = i;             ans[i] = Math.Min(ans[i], prev-i);         }                    foreach (var i in ans)             Console.Write(i + " ");     }            // Driver code     public static void Main(String[] args)     {         String S = "geeksforgeeks";         char X = 'g';         shortestDistance(S, X);     } }    // This code is contributed by // sanjeev2552

Output:

[0, 1, 2, 3, 4, 3, 2, 1, 0, 1, 2, 3, 4]

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