1903. Maximum odd number in string

Address ：

Power button https://leetcode-cn.com/problems/largest-odd-number-in-string/submissions/

subject ：

Give you a string num , Represents a large integer . Please write in the string num All of the   Non empty substring To find out in the The odd number with the largest value , And returns... As a string . If there is no odd number , Then return an empty string "" .

Substring Is a continuous sequence of characters in a string .

Example 1：

Input ：num = "52" Output ："5" explain ： Non empty substrings have only "5"、"2" and "52" ."5" It's the only odd number .

Example 2：

Input ：num = "4206" Output ："" explain ： stay "4206" There is no odd number in .

Example 3：

Input ：num = "35427" Output ："35427" explain ："35427" It's an odd number in itself .

Tips ：

1 <= num.length <= 105 num Composed of numbers only and without leading zeros

source ： Power button （LeetCode）
link ：https://leetcode-cn.com/problems/largest-odd-number-in-string
Copyright belongs to the network . For commercial reprint, please contact the official authority , Non-commercial reprint please indicate the source .

Ideas ：

Odd number means that a bit is odd , As for the biggest , That is to regard the previous numbers as one （ If there is a previous number ）

So the topic is very simple , Find odd numbers in reverse order , If you find that , Just copy forward

Method 1 、 Find the position where odd numbers appear in reverse order

char odd[100001];

char * largestOddNumber(char * num){
	int slen = strlen(num);
	
	memset(odd, 0, sizeof(char));
	odd[105] = '\0';
	
	for(int i=slen-1, j=0; i>=0; i--, j++)
	{
		int ch = num[i] - '0';
		if(ch & 1)
		{
			strncpy(odd, num, slen - j);
			odd[slen-j]='\0';
            break;
		}
	}
	
	return odd;
}

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