python C++速解Leetcode 1544 make the string great

python C++速解Leetcode 1544 make  the string great

基本上算是stack解法，但實作的語言C, C++, python只需要善用個別字串的特性，無須使用stack，大幅加快計算速度，C語言解答請進，並加上最佳C++解

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It is basically a stack solution, but the implementation languages ​​​​C, C++, and python only need to make good use of the characteristics of individual strings without using stack, which greatly speeds up calculations. C solution is not in the film.

[codes on Leetcode]https://leetcode.com/problems/make-the-string-great/solutions/4975169/c-c-python-use-string-list-as-stack-in-place-0ms-beats-100/

[Leetcode程式]https://www.youtube.com/watch?v=XpO9wcI8KAg&list=PLYRlUBnWnd5IdDHk2BjqXwesydU17z_xk

#pragma GCC optimize("O3", "unroll-loops")
char* makeGood(char* s) {
    char* ans=(char*)malloc(101);//Must be dynamicall malloc
    int top=-1;
    for(register int i=0; s[i]!='\0'; i++){//strlen has O(n) TC
        if (top!=-1 && abs(s[i]-ans[top])==32)
            top--;
        else
            ans[++top]=s[i];
    }
    ans[top+1]='\0';//C-string terminal char
    return ans;
}

//最佳C++解

class Solution {
public:
    string makeGood(string& s) {
        int n=s.size(), top=-1;
        for(char c: s)
            if (top!=-1 && (c^s[top])==32)
                top--;
            else 
                s[++top]=c;
        s.resize(top+1);
        return s;
    }
};