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[LeetCode]ZigZag Conversion

The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility)

P   A   H   NA P L S I I GY   I   R

And then read line by line: "PAHNAPLSIIGYIR"

 

Write the code that will take a string and make this conversion given a number of rows:

string convert(string text, int nRows);

convert("PAYPALISHIRING", 3) should return "PAHNAPLSIIGYIR".

 

思路,用一个idx 从0-->(nRows-1)---->0 来回往返,将对应的字符加入到strs[idx]的字符串中,最后汇总所有的字符串,

 

注意,当nRows == 1的情况需要特使处理,否则idx-- 后,idx变成-1,会越界crash

class Solution {    public:        string convert(string s, int nRows) {            if(nRows == 1)                return s;                            vector<string> strs;            strs.resize(nRows);            string result;            int idx = 0;            bool upOrDown = false;// false--down, true--up            for(size_t i = 0; i< s.size(); i++)            {                   strs[idx] += s[i];                if(upOrDown == false)                {                       if(idx == (nRows-1))                    {                           upOrDown = true;                        idx--;                    }                       else                    {                           idx++;                    }                   }                   else                {                       if(idx == 0)                    {                           upOrDown = false;                        idx++;                    }                       else                    {                           idx--;                    }                }            }            for(size_t i = 0; i< strs.size(); i++)            {                result += strs[i];            }            return result;        }};

 

[LeetCode]ZigZag Conversion