1044. Shopping in Mars (25)解题报告

#define _CRT_SECURE_NO_WARNINGS
#include <cstdio>
#include <cstdlib>
#include <iostream>

struct node {
int data;
struct node *left, *right, *parent;
};

node *rebuild1(int left1, int right1, int left2, int right2);
node *rebuild2(int left1, int right1, int left2, int right2);
void posttraversal(node *root);
void deletree(node *root);
int cmp1(const void *v1, const void *v2) {
return *((int *)v1) - *((int *)v2);
}
int cmp2(const void *v1, const void *v2) {
return *((int *)v2) - *((int *)v1);
}
int find1(int aim, int arr[], int begin, int end) {
int i;
i = begin;
while (i <= end) {
if (arr[i] == aim) {
return i;
}
i++;
}
return -1;
}
int find2(int aim, int arr[], int begin, int end) {
int i;
i = end;
while (i >= begin) {
if (arr[i] == aim) {
return i;
}
i--;
}
return -1;
}

int arr1[1000], arr2[1000], arr3[1000];
bool flag1 = true, flag2 = true;
int main(void) {
int n, i;
scanf("%d", &n);
for (i = 0; i < n; i++) {
scanf("%d", arr1 + i);
arr2[i] = arr3[i] = arr1[i];
}
qsort(arr2, n, sizeof(int), cmp1);
qsort(arr3, n, sizeof(int), cmp2);

node *root1, *root2;
root1 = rebuild1(0, n - 1, 0, n - 1);
root2 = rebuild2(0, n - 1, 0, n - 1);
if (flag1) {
puts("YES");
posttraversal(root1->left);
posttraversal(root1->right);
printf("%d\n", root1->data);
}
else if (flag2) {
puts("YES");
posttraversal(root2->left);
posttraversal(root2->right);
printf("%d\n", root2->data);
}
else {
puts("NO");
}
deletree(root1);
deletree(root2);
return 0;
}

node *rebuild1(int left1, int right1, int left2, int right2) {
if (left1 > right1) {
return nullptr;
}
else if (left1 == right1) {
if (arr1[left1] != arr2[left2] || right2 != left2) {
flag1 = false;
return nullptr;
}
node *tmp = new node;
tmp->data = arr1[left1];
tmp->left = nullptr;
tmp->right = nullptr;
return tmp;
}
else if (right1 - left1 == right2 - left2) {
node *tmp = new node;
tmp->data = arr1[left1];
int index = find1(arr1[left1], arr2, left2, right2);
if (index == -1) {
flag1 = false;
return nullptr;
}
tmp->left = rebuild1(left1 + 1, left1 + index - left2, left2, index - 1);
tmp->right = rebuild1(left1 + index - left2 + 1, right1, index + 1, right2);
return tmp;
}
else {
flag1 = false;
return nullptr;
}
}

node *rebuild2(int left1, int right1, int left2, int right2) {
if (left1 > right1) {
return nullptr;
}
else if (left1 == right1) {
if (arr1[left1] != arr3[left2] || right2 != left2) {
flag2 = false;
return nullptr;
}
node *tmp = new node;
tmp->data = arr1[left1];
tmp->left = nullptr;
tmp->right = nullptr;
return tmp;
}
else if (right1 - left1 == right2 - left2) {
node *tmp = new node;
tmp->data = arr1[left1];
int index = find2(arr1[left1], arr3, left2, right2);
if (index == -1) {
flag2 = false;
return nullptr;
}
tmp->left = rebuild2(left1 + 1, left1 + index - left2, left2, index - 1);
tmp->right = rebuild2(left1 + index - left2 + 1, right1, index + 1, right2);
return tmp;
}
else {
flag2 = false;
return nullptr;
}
}
void posttraversal(node *root) {
if (!root) {
return;
}
else {
posttraversal(root->left);
posttraversal(root->right);
printf("%d ", root->data);
return;
}
}
void deletree(node *root) {
if (!root) {
return;
}
else {
deletree(root->left);
deletree(root->right);
free(root);
return;
}
}