leetcode——解碼方法

// 爬樓梯問題

int numDecodings(char * s){
    
    if(s[0] == '0' || s[0] == 0 ) return 0;
    
    int pre = 1,cur = 1;
    int temp;
    int i;
    
    for( i = 1; s[i] != 0; i++){
        
        temp = cur;
        
        if(s[i] == '0')
            if(s[i-1] == '1' || s[i-1] == '2') cur = pre;
            else return 0;
                    
        else if( s[i - 1] == '1' || (s[i - 1] == '2' && s[i] >= '1' && s[i] <= '6') )
            cur = cur + pre;
        pre = temp;
    }
    
    return cur;
    
}