LeetCode – Find And Replace in String (Java)

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To some string S, we will perform some replacement operations that replace groups of letters with new ones (not necessarily the same size).

Each replacement operation has 3 parameters: a starting index i, a source word x and a target word y. The rule is that if x starts at position i in the original string S, then we will replace that occurrence of x with y. If not, we do nothing.

For example, if we have S = “abcd” and we have some replacement operation i = 2, x = “cd”, y = “ffff”, then because “cd” starts at position 2 in the original string S, we will replace it with “ffff”.

Java Solution

public String findReplaceString(String S, int[] indexes, String[] sources, String[] targets) {
    StringBuilder sb = new StringBuilder();
    TreeMap<Integer, String[]> map = new TreeMap<>();
    for (int i = 0; i < indexes.length; i++) {
        map.put(indexes[i], new String[]{sources[i], targets[i]});
    }
 
    int prev = 0;
 
    for (Map.Entry<Integer, String[]> entry : map.entrySet()) {
        int startIndex = entry.getKey();
        int endIndex = startIndex + entry.getValue()[0].length();
 
        if (prev != startIndex) {
            sb.append(S.substring(prev, startIndex));
        }
 
        String org = S.substring(startIndex, endIndex);
        if (org.equals(entry.getValue()[0])) {
            sb.append(entry.getValue()[1]);
            prev = endIndex;
        } else {
            sb.append(org);
            prev = endIndex;
        }
 
    }
 
    if (prev < S.length()) {
        sb.append(S.substring(prev));
    }
 
    return sb.toString();
}

2 thoughts on “LeetCode – Find And Replace in String (Java)”

  1. The provided Java code implements a function called findReplaceString that performs replacement operations on a given input string S. These replacement operations are specified by arrays containing starting indexes, source words, and target words. The code constructs a modified string based on these operations and ensures that replacements occur in the correct order. Mulesoft Training


  2. class Solution {
    public:
    string findReplaceString(string S, vector& indexes, vector& sources, vector& targets) {
    unordered_map mp;
    for(int i = 0; i < indexes.size(); i++) mp[indexes[i]] = i;
    string ans = "";
    for(int i = 0; i = S.size()) {
    ans += S[i];
    }
    else {
    string part = S.substr(i, sources[mp[i]].size());
    if(part == sources[mp[i]]) {
    ans += targets[mp[i]];
    i += part.size() - 1;
    }
    else ans += S[i];
    }
    }
    return ans;
    }
    };

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