Partition List

标签：

Given a linked list and a value x, partition it such that all nodes less than x come before nodes greater than or equal to x.

You should preserve the original relative order of the nodes in each of the two partitions.

For example,
Given 1->4->3->2->5->2 and x = 3,
return 1->2->2->4->3->5.

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

typedef struct ListNode {
   int val;
   struct ListNode *next;
}ListNode;

ListNode *partition(ListNode *head, int x) {
    ListNode *less = NULL, *bigger = NULL, *p;
    ListNode *less_index , *bigger_index;
    int less_cnt = 0, bigger_cnt = 0;
    if(head == NULL) return NULL;
    for(p = head; p != NULL; p = p->next) {
        if(p->val < x) {
            if(less_cnt == 0) less_index = less = p; 
            else {
                less_index->next = p;
                less_index = p;
            }
            less_cnt++;
        }
        else {
            if(bigger_cnt == 0) bigger_index = bigger = p;
            else {
                bigger_index->next = p;
                bigger_index = p;
            }
            bigger_cnt++;
        }
    }
    if(less != NULL) less_index->next = bigger;
    else less = bigger;
    if(bigger != NULL) bigger_index->next = NULL;
    return less;
}

void main() {
    ListNode *head, *p1, *p2;
    int i = 0;
    p1 = p2 = (ListNode *)malloc(sizeof(ListNode));
    scanf("%d", &p1->val);
    while(p1->val != -1) {
        i++;
        if(i == 1) head = p1;
        else p2->next = p1;
        p2 = p1;
        p1 = (ListNode *)malloc(sizeof(ListNode));
        scanf("%d", &p1->val);
    }
    p2->next = NULL;
    for(p1 = head; p1 != NULL; p1 = p1->next) printf("%d ", p1->val);
    printf("\n");
    partition(head, 0);
}

Partition List

标签：

原文地址：http://blog.csdn.net/uj_mosquito/article/details/42971455