leetcode 日经贴，Cpp code -ZigZag Conversion

ZigZag Conversion

class Solution {public:    string convert(string s, int nRows) {        string ret = "";        if (nRows <= 1) {            return s;        }        int n = s.length();        ret.resize(n);        int intervals[2];        int itr = 0;        for (int i = 0; i < nRows; ++i) {            if (i == 0 || i == nRows - 1) {                intervals[0] = intervals[1] = 2 * (nRows - 1);            } else {                intervals[0] = 2 * (nRows - 1 - i);                intervals[1] = 2 * i;            }            int j = i, k = 0;            while (j < n) {                ret[itr++] = s[j];                j += intervals[k];                k = 1 - k;            }        }        return ret;    }};