Description
Given an array of n integers nums, a 132 pattern is a subsequence of three integers nums[i], nums[j] and nums[k] such that i < j < k and nums[i] < nums[k] < nums[j].
Return true if there is a 132 pattern in nums, otherwise, return false.
Example 1:
Input: nums = [1,2,3,4]
Output: false
Explanation: There is no 132 pattern in the sequence.
Example 2:
Input: nums = [3,1,4,2]
Output: true
Explanation: There is a 132 pattern in the sequence: [1, 4, 2].
Example 3:
Input: nums = [-1,3,2,0]
Output: true
Explanation: There are three 132 patterns in the sequence: [-1, 3, 2], [-1, 3, 0] and [-1, 2, 0].
Constraints:
n == nums.length1 <= n <= 2 * 105-109 <= nums[i] <= 109
Solutions
Solution 1
PythonJavaC++GoTypeScriptRust
class Solution:
def find132pattern(self, nums: List[int]) -> bool:
vk = -inf
stk = []
for x in nums[::-1]:
if x < vk:
return True
while stk and stk[-1] < x:
vk = stk.pop()
stk.append(x)
return False(code-box)
class Solution {
public boolean find132pattern(int[] nums) {
int vk = -(1 << 30);
Deque<Integer> stk = new ArrayDeque<>();
for (int i = nums.length - 1; i >= 0; --i) {
if (nums[i] < vk) {
return true;
}
while (!stk.isEmpty() && stk.peek() < nums[i]) {
vk = stk.pop();
}
stk.push(nums[i]);
}
return false;
}
}(code-box)
class Solution {
public:
bool find132pattern(vector<int>& nums) {
int vk = INT_MIN;
stack<int> stk;
for (int i = nums.size() - 1; ~i; --i) {
if (nums[i] < vk) {
return true;
}
while (!stk.empty() && stk.top() < nums[i]) {
vk = stk.top();
stk.pop();
}
stk.push(nums[i]);
}
return false;
}
};(code-box)
func find132pattern(nums []int) bool {
vk := -(1 << 30)
stk := []int{}
for i := len(nums) - 1; i >= 0; i-- {
if nums[i] < vk {
return true
}
for len(stk) > 0 && stk[len(stk)-1] < nums[i] {
vk = stk[len(stk)-1]
stk = stk[:len(stk)-1]
}
stk = append(stk, nums[i])
}
return false
}(code-box)
function find132pattern(nums: number[]): boolean {
let vk = -Infinity;
const stk: number[] = [];
for (let i = nums.length - 1; i >= 0; --i) {
if (nums[i] < vk) {
return true;
}
while (stk.length && stk[stk.length - 1] < nums[i]) {
vk = stk.pop()!;
}
stk.push(nums[i]);
}
return false;
}(code-box)
impl Solution {
pub fn find132pattern(nums: Vec<i32>) -> bool {
let n = nums.len();
let mut vk = i32::MIN;
let mut stk = vec![];
for i in (0..n).rev() {
if nums[i] < vk {
return true;
}
while !stk.is_empty() && stk.last().unwrap() < &nums[i] {
vk = stk.pop().unwrap();
}
stk.push(nums[i]);
}
false
}
}(code-box)
Solution 2
PythonJavaC++GoTypeScript
class BinaryIndexedTree:
def __init__(self, n):
self.n = n
self.c = [0] * (n + 1)
def update(self, x, delta):
while x <= self.n:
self.c[x] += delta
x += x & -x
def query(self, x):
s = 0
while x:
s += self.c[x]
x -= x & -x
return s
class Solution:
def find132pattern(self, nums: List[int]) -> bool:
s = sorted(set(nums))
n = len(nums)
left = [inf] * (n + 1)
for i, x in enumerate(nums):
left[i + 1] = min(left[i], x)
tree = BinaryIndexedTree(len(s))
for i in range(n - 1, -1, -1):
x = bisect_left(s, nums[i]) + 1
y = bisect_left(s, left[i]) + 1
if x > y and tree.query(x - 1) > tree.query(y):
return True
tree.update(x, 1)
return False(code-box)
class BinaryIndexedTree {
private int n;
private int[] c;
public BinaryIndexedTree(int n) {
this.n = n;
c = new int[n + 1];
}
public void update(int x, int v) {
while (x <= n) {
c[x] += v;
x += x & -x;
}
}
public int query(int x) {
int s = 0;
while (x > 0) {
s += c[x];
x -= x & -x;
}
return s;
}
}
class Solution {
public boolean find132pattern(int[] nums) {
int[] s = nums.clone();
Arrays.sort(s);
int n = nums.length;
int m = 0;
int[] left = new int[n + 1];
left[0] = 1 << 30;
for (int i = 0; i < n; ++i) {
left[i + 1] = Math.min(left[i], nums[i]);
if (i == 0 || s[i] != s[i - 1]) {
s[m++] = s[i];
}
}
BinaryIndexedTree tree = new BinaryIndexedTree(m);
for (int i = n - 1; i >= 0; --i) {
int x = search(s, m, nums[i]);
int y = search(s, m, left[i]);
if (x > y && tree.query(x - 1) > tree.query(y)) {
return true;
}
tree.update(x, 1);
}
return false;
}
private int search(int[] nums, int r, int x) {
int l = 0;
while (l < r) {
int mid = (l + r) >> 1;
if (nums[mid] >= x) {
r = mid;
} else {
l = mid + 1;
}
}
return l + 1;
}
}(code-box)
class BinaryIndexedTree {
public:
BinaryIndexedTree(int n) {
this->n = n;
this->c = vector<int>(n + 1, 0);
}
void update(int x, int val) {
while (x <= n) {
c[x] += val;
x += x & -x;
}
}
int query(int x) {
int s = 0;
while (x > 0) {
s += c[x];
x -= x & -x;
}
return s;
}
private:
int n;
vector<int> c;
};
class Solution {
public:
bool find132pattern(vector<int>& nums) {
vector<int> s = nums;
sort(s.begin(), s.end());
s.erase(unique(s.begin(), s.end()), s.end());
BinaryIndexedTree tree(s.size());
int n = nums.size();
int left[n + 1];
memset(left, 63, sizeof(left));
for (int i = 0; i < n; ++i) {
left[i + 1] = min(left[i], nums[i]);
}
for (int i = nums.size() - 1; ~i; --i) {
int x = lower_bound(s.begin(), s.end(), nums[i]) - s.begin() + 1;
int y = lower_bound(s.begin(), s.end(), left[i]) - s.begin() + 1;
if (x > y && tree.query(x - 1) > tree.query(y)) {
return true;
}
tree.update(x, 1);
}
return false;
}
};(code-box)
type BinaryIndexedTree struct {
n int
c []int
}
func newBinaryIndexedTree(n int) *BinaryIndexedTree {
c := make([]int, n+1)
return &BinaryIndexedTree{n, c}
}
func (this *BinaryIndexedTree) update(x, val int) {
for x <= this.n {
this.c[x] += val
x += x & -x
}
}
func (this *BinaryIndexedTree) query(x int) int {
s := 0
for x > 0 {
s += this.c[x]
x -= x & -x
}
return s
}
func find132pattern(nums []int) bool {
n := len(nums)
s := make([]int, n)
left := make([]int, n+1)
left[0] = 1 << 30
copy(s, nums)
sort.Ints(s)
m := 0
for i := 0; i < n; i++ {
left[i+1] = min(left[i], nums[i])
if i == 0 || s[i] != s[i-1] {
s[m] = s[i]
m++
}
}
s = s[:m]
tree := newBinaryIndexedTree(m)
for i := n - 1; i >= 0; i-- {
x := sort.SearchInts(s, nums[i]) + 1
y := sort.SearchInts(s, left[i]) + 1
if x > y && tree.query(x-1) > tree.query(y) {
return true
}
tree.update(x, 1)
}
return false
}(code-box)
class BinaryIndextedTree {
n: number;
c: number[];
constructor(n: number) {
this.n = n;
this.c = new Array(n + 1).fill(0);
}
update(x: number, val: number): void {
while (x <= this.n) {
this.c[x] += val;
x += x & -x;
}
}
query(x: number): number {
let s = 0;
while (x) {
s += this.c[x];
x -= x & -x;
}
return s;
}
}
function find132pattern(nums: number[]): boolean {
let s: number[] = [...nums];
s.sort((a, b) => a - b);
const n = nums.length;
const left: number[] = new Array(n + 1).fill(1 << 30);
let m = 0;
for (let i = 0; i < n; ++i) {
left[i + 1] = Math.min(left[i], nums[i]);
if (i == 0 || s[i] != s[i - 1]) {
s[m++] = s[i];
}
}
s = s.slice(0, m);
const tree = new BinaryIndextedTree(m);
for (let i = n - 1; i >= 0; --i) {
const x = search(s, nums[i]);
const y = search(s, left[i]);
if (x > y && tree.query(x - 1) > tree.query(y)) {
return true;
}
tree.update(x, 1);
}
return false;
}
function search(nums: number[], x: number): number {
let l = 0,
r = nums.length - 1;
while (l < r) {
const mid = (l + r) >> 1;
if (nums[mid] >= x) {
r = mid;
} else {
l = mid + 1;
}
}
return l + 1;
}(code-box)
