[LeetCode] 179. Largest Number

轉自LeetCode

Given a list of non negative integers, arrange them such that they form the largest number.

For example, given [3, 30, 34, 5, 9], the largest formed number is 9534330.

Note: The result may be very large, so you need to return a string instead of an integer.

<Solution>

這題是要把非負數的數字們，組成一個最大的數字

想法如下

• 先將數字都轉成字串

• 透過字串的比對，來排序字串。例如 ["30", "9"]，因為 "309" < "930"，所以排序結果會是 ["9", "30"]

code如下

	class Solution {
	public:
	string largestNumber(vector<int>& nums) {
	string ans;
	vector<string> numStr;
	//>> change int to string
	for(const auto &n : nums) {
	numStr.push_back(to_string(n));
	}
	//>> sorting
	//>> ex. "30" and "9" => "309" < "930"
	//>> therefore, "9" comes before "30"
	sort(numStr.begin(), numStr.end(), [](string a, string b) -> bool {
	return a+b > b+a;
	});
	//>> combine to ans
	for(const auto &s : numStr) {
	ans += s;
	}
	//>> eliminate redundant 0s
	return (ans[0] == '0') ? "0" : ans;
	}
	};

view raw combineIntToLargetNumber_1.cpp hosted with ❤ by GitHub