763. dividing alphabetic intervals

763. Division of alphabet

character string S It's made up of lowercase letters . We're going to divide this string into as many pieces as possible , The same letter can appear in at most one segment . Returns a list representing the length of each string fragment .

Example ：

Input ：S = “ababcbacadefegdehijhklij”
Output ：[9,7,8]
explain ：
The result is “ababcbaca”, “defegde”, “hijhklij”.
Each letter appears in at most one segment .
image “ababcbacadefegde”, “hijhklij” The division is wrong , Because the number of segments is small .

We can use two auxiliary arrays for this problem , It can solve the problem well ：

/** * Note: The returned array must be malloced, assume caller calls free(). */
int* partitionLabels(char * s, int* returnSize){
    
    int r[26];
     int r_t[26];
    int i;
    int *re=(int *)malloc(sizeof(int)*26);
    for(i=0;i<26;i++){
    
        r[i]=0;
        r_t[i]=0;
    }
    i=0;
    while(s[i]!='\0'){
    
        r[s[i]-'a']++;
        i++;
    }
    int sum=0;
    int now=-1;
    i=0;
    int size=0;
    while(s[i]!='\0'){
    
          r_t[s[i]-'a']++;
          sum++;
        if( r_t[s[i]-'a']==r[s[i]-'a']){
    
            sum=sum-r[s[i]-'a'];
            if(sum==0){
    
                re[size++]=i-now;
                now=i;
            }
        }
        i++;
       
    }
    *returnSize=size;
    return re;

}