306. Additive Number | Java最短代码实现

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原题链接：306. Additive Number

【思路】

    public boolean isAdditiveNumber(String num) {        for (int i = 1; i <= num.length() / 2; i++)            for (int j = 1; j + i < num.length(); j++)                if (isValid(num, num.substring(0, i), num.substring(i, i + j), i + j)) return true;        return false;    }    public boolean isValid(String num, String first, String second, int index) {        if (first.length() > 1 && first.startsWith("0")            || second.length() > 1 && second.startsWith("0")) return false;        if (index == num.length()) return true;        long sum = Long.parseLong(first) + Long.parseLong(second);        if (num.startsWith(sum + "", index))            if(isValid(num, second, sum + "", index + (sum + "").length())) return true;        return false;    }

37 / 37 test cases passed. Runtime: 3 ms Your runtime beats 29.26% of javasubmissions.

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