93. 复原IP地址

/**
 * Note: The returned array must be malloced, assume caller calls free().
 */
 #define MAX_IP_ADR 1000
 #if 0
 int IsValid(char* s, int i, int j)
{
    int num = 0;
    int k;
    if (j - i > 3) {
        return -1;
    }
    // 不允许0开头
    for (k = i; k < j; k++) {
        num = num * 10 + (s[k] - ‘0‘);
    }
    if ((num != 0 && s[i] == ‘0‘) || (num == 0 && (j - i) > 1)) {
        return -1;
    }
    if (num >= 0 && num <= 255) {
        //printf("the num is %d\n", num);
        return num;
    }
    return -1;
}
#endif
#if 1
 int IsValid(char *s,int start,int end){
     int len=strlen(s);
     int tmp,num=0;
    // 不可能是四位数
     if(end-start>3){
         return -1;
     }
   
     for(int i=start;i<end;i++){
         
         num=num*10+s[i]-‘0‘;
     }
     //不能出现08.07类似情况，后面是000
     if(((num!=0)&&(s[start]-‘0‘==0))||((num == 0 && (end - start) > 1))){
         return -1;
     }
    
     if((num>255)||(num<0)){
         
         return -1;
     }
     return num;

 }
 #endif
char ** restoreIpAddresses(char * s, int* returnSize){
    int len=strlen(s);
    
    /* "xxx.xxx.xxx.xxx" */
    int ipaddress[1000][4]={0};
    int cnt=0;
    for(int i=1;i<=3;i++){
        for(int j=i+1;j<len;j++){
            for(int k=j+1;k<len;k++){
                //printf("i%d j%d k%d\n",i,j,k);
                if(((ipaddress[cnt][0]=IsValid(s,0,i))!=-1)&&((ipaddress[cnt][1]=IsValid(s,i,j))!=-1)&&(((ipaddress[cnt][2]=IsValid(s,j,k))!=-1)&&((ipaddress[cnt][3]=IsValid(s,k,len))!=-1))){
                    cnt++;
                }
                
            }

        }
    }
    //printf("%d/r/n",cnt);
    char **ipadr=(char **)malloc(sizeof(char *)*cnt);
    for(int i=0;i<cnt;i++){
        ipadr[i]=(char *)malloc(sizeof(char)*16);
        //printf("%d %d %d %d\n",ipaddress[i][0],ipaddress[i][1],ipaddress[i][2],ipaddress[i][3]);
       sprintf(ipadr[i],"%d.%d.%d.%d",ipaddress[i][0],ipaddress[i][1],ipaddress[i][2],ipaddress[i][3]); 
    }
    *returnSize=cnt;
    return ipadr;
}

//要考虑sprintf的使用