LeetCode-in-Java

816. Ambiguous Coordinates

Medium

We had some 2-dimensional coordinates, like "(1, 3)" or "(2, 0.5)". Then, we removed all commas, decimal points, and spaces and ended up with the string s.

• For example, "(1, 3)" becomes s = "(13)" and "(2, 0.5)" becomes s = "(205)".

Return a list of strings representing all possibilities for what our original coordinates could have been.

Our original representation never had extraneous zeroes, so we never started with numbers like "00", "0.0", "0.00", "1.0", "001", "00.01", or any other number that can be represented with fewer digits. Also, a decimal point within a number never occurs without at least one digit occurring before it, so we never started with numbers like ".1".

The final answer list can be returned in any order. All coordinates in the final answer have exactly one space between them (occurring after the comma.)

Example 1:

Input: s = “(123)”

Output: [“(1, 2.3)”,”(1, 23)”,”(1.2, 3)”,”(12, 3)”]

Example 2:

Input: s = “(0123)”

Output: [“(0, 1.23)”,”(0, 12.3)”,”(0, 123)”,”(0.1, 2.3)”,”(0.1, 23)”,”(0.12, 3)”]

Explanation: 0.0, 00, 0001 or 00.01 are not allowed.

Example 3:

Input: s = “(00011)”

Output: [“(0, 0.011)”,”(0.001, 1)”]

Constraints:

• 4 <= s.length <= 12
• s[0] == '(' and s[s.length - 1] == ')'.
• The rest of s are digits.

Solution

import java.util.ArrayList;
import java.util.List;

@SuppressWarnings("java:S107")
public class Solution {
    public List<String> ambiguousCoordinates(String s) {
        char[] sc = s.toCharArray();
        List<String> result = new ArrayList<>();
        StringBuilder sb = new StringBuilder();
        for (int commaPos = 2; commaPos < sc.length - 1; commaPos++) {
            if (isValidNum(sc, 1, commaPos - 1)) {
                if (isValidNum(sc, commaPos, sc.length - 2)) {
                    buildNums(result, sb, sc, commaPos - 1, 0, commaPos, sc.length - 2, 0);
                }
                for (int dp2Idx = commaPos + 1; dp2Idx < sc.length - 1; dp2Idx++) {
                    if (isValidDPNum(sc, commaPos, sc.length - 2, dp2Idx)) {
                        buildNums(result, sb, sc, commaPos - 1, 0, commaPos, sc.length - 2, dp2Idx);
                    }
                }
            }
            for (int dp1Idx = 2; dp1Idx < commaPos; dp1Idx++) {
                if (isValidDPNum(sc, 1, commaPos - 1, dp1Idx)) {
                    if (isValidNum(sc, commaPos, sc.length - 2)) {
                        buildNums(result, sb, sc, commaPos - 1, dp1Idx, commaPos, sc.length - 2, 0);
                    }
                    for (int dp2Idx = commaPos + 1; dp2Idx < sc.length - 1; dp2Idx++) {
                        if (isValidDPNum(sc, commaPos, sc.length - 2, dp2Idx)) {
                            buildNums(
                                    result,
                                    sb,
                                    sc,
                                    commaPos - 1,
                                    dp1Idx,
                                    commaPos,
                                    sc.length - 2,
                                    dp2Idx);
                        }
                    }
                }
            }
        }
        return result;
    }

    private boolean isValidNum(char[] sc, int startIdx, int lastIdx) {
        return sc[startIdx] != '0' || lastIdx - startIdx == 0;
    }

    private boolean isValidDPNum(char[] sc, int startIdx, int lastIdx, int dpIdx) {
        return (sc[startIdx] != '0' || dpIdx - startIdx == 1) && sc[lastIdx] != '0';
    }

    private void buildNums(
            List<String> result,
            StringBuilder sb,
            char[] sc,
            int last1Idx,
            int dp1Idx,
            int start2Idx,
            int last2Idx,
            int dp2Idx) {
        sb.setLength(0);
        sb.append('(');
        if (dp1Idx == 0) {
            sb.append(sc, 1, last1Idx - 1 + 1);
        } else {
            sb.append(sc, 1, dp1Idx - 1).append('.').append(sc, dp1Idx, last1Idx - dp1Idx + 1);
        }
        sb.append(',').append(' ');
        if (dp2Idx == 0) {
            sb.append(sc, start2Idx, last2Idx - start2Idx + 1);
        } else {
            sb.append(sc, start2Idx, dp2Idx - start2Idx)
                    .append('.')
                    .append(sc, dp2Idx, last2Idx - dp2Idx + 1);
        }
        sb.append(')');
        result.add(sb.toString());
    }
}

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