leetcode-0214

题目

最短回文串

关键词

回文字串

思路：

将字符串倒序，再从源字串依次比较，找到重叠位置合并

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

//#define MY_DEBUG printf
#define MY_DEBUG
#define MLOGI       MY_DEBUG
#define MLOGE       MY_DEBUG

char * shortestPalindrome(char * s)
{
    if (s == NULL) {
        return NULL;
    }
    int srcLen = strlen(s);
    if (srcLen == 0) {
        return s;
    }
    if (srcLen == 1) {
        return s;
    }
    char *retBuf = (char *)malloc(srcLen * 2);
    if (retBuf == NULL) {
        return NULL;
    }
    int i = 0;
    while(s[i] != '\0') {
        retBuf[i] = s[srcLen - i - 1];
        i ++;
    }
    for (i = 0; i < srcLen; i++) {
        if (memcmp(retBuf + i, s, srcLen - i - 1) == 0) {
            snprintf(retBuf + i, srcLen * 2 - i, "%s", s);
            MLOGI("[%s_%d] i=%d, retBuf:%s\n", __func__, __LINE__, i, retBuf);
            break;
        }
    }
    return retBuf;
}