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【leetcode】ZigZag Conversion

2024-07-17 01:27:34   220人阅读

题目：

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   N
A P L S I I G
Y   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".

解析：考察对字符串的操作，将一个字符串竖着写成nRows行，写成若干个倒着的Z形状，再一行行横着输出。注意下面代码nRows=1的时候，要特别处理，否则会有memory limited exceed的错误。C++ AC代码如下：
class Solution {
public:
    string convert(string s, int nRows) {
        string result;
        if(nRows<2) return s;
        int zigSize = 2 * nRows -2;
        for(int i=0;i<nRows;i++){
            for(int j=i;j<s.length();j+=zigSize){
                result.append(1,s[j]);
                if(i!=0 && i!=nRows-1 && j + zigSize - 2* i < s.length()){
                    result.append(1,s[j + zigSize - 2* i]);
                }
            }
        }
        return result;
    }
};


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