Leetcode hot 100
双指针
283.移动零
class Solution {
public:
void moveZeroes(vector& nums) {
int cnt = 0;
for(vector::iterator it = nums.begin(); it != nums.end(); ){
if(*it == 0) it = nums.erase(it),cnt++;
else it++;
}
while(cnt--){
nums.push_back(0);
}
}
}; 11.盛水最多的容器
class Solution {
public:
int maxArea(vector& height) {
int l = 0, r = height.size()-1;
int ans = 0;
while(l < r){
int t = min(height[l], height[r]) * (r-l) ;
ans = max(ans, t);
if(height[l] < height[r]) l++;
else r--;
}
return ans;
}
}; 53. 最大子数组和
class Solution {
public:
int maxSubArray(vector& nums) {
return maxx(nums, 0, nums.size() - 1);
}
int maxx(vector& nums, int l, int r) {
if (l > r) return 0;
if (l == r) {
return nums[l];
}
int mid = (l + r) / 2;
int ret = maxx(nums, l, mid);
if(mid + 1 <= r)ret = max(ret, maxx(nums, mid + 1, r));
int i = mid-1, j = mid+1;
int tmp = nums[mid], maxone = tmp;
while ( i >= l ) {
tmp += nums[i];
if (tmp >= maxone)
maxone = max(maxone, tmp);
i--;
}
tmp = maxone;
while ( j <= r ) {
tmp += nums[j];
if ( tmp >= maxone)
maxone = max(maxone, tmp);
j++;
}
return max(ret, maxone);
}
};
56. 合并区间
class Solution {
public:
static bool cmp(vector a, vector b){
if(a[0] != b[0]) return a[0] < b[0];
if(a[1] != b[1]) return a[1] < b[1];
return false;
}
vector> merge(vector< vector > intervals) {
vector> ret ;
// vector tmp;
sort(intervals.begin(), intervals.end(), cmp);
int l = intervals[0][0], r = intervals[0][1];
for(int i = 1; i< intervals.size(); i++){
// cout< 160. 相交链表
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode *getIntersectionNode(ListNode *headA, ListNode *headB) {
ListNode* p = headA, *q = NULL;
int len1 = 0,len2 = 0;
while(p){
len1++;
p = p->next;
}
p = headB;
while(p){
len2 ++;
p = p->next;
}
p = headA;
q = headB;
if(len1 > len2) {
int n = len1 - len2;
while(n--) p = p->next;
}
else{
int n = len2 - len1;
while(n--) q = q->next;
}
while(p != q){
p = p->next;
q = q->next;
}
return p;
}
};141. 环形链表
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
bool hasCycle(ListNode *head) {
set st;
ListNode *p = head;
while(p != NULL){
if(st.find(p) == st.end()) st.insert(p);
else return true;
p = p->next;
}
return false;
}
}; 142. 环形链表 II
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode *detectCycle(ListNode *head) {
map mp;
ListNode * ret = head;
int idx = 0;
while(ret != NULL){
cout<next;
}
return NULL;
}
};
2. 两数相加
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode() : val(0), next(nullptr) {}
* ListNode(int x) : val(x), next(nullptr) {}
* ListNode(int x, ListNode *next) : val(x), next(next) {}
* };
*/
class Solution {
public:
ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
ListNode* p, *q, *tmp, *tmp2;
p = l1;
q = l2;
int c = 0;
tmp2 = p;
while(p != NULL && q!=NULL){
tmp = p;
p->val = p->val + q->val + c;
c = p->val / 10;
p->val %= 10;
p = p->next;
q = q->next;
}
while(p != NULL){
tmp = p;
p->val += c;
c = p->val / 10;
p->val %= 10;
p = p->next;
}
if(q!=NULL){
tmp->next = q;
}
while(q != NULL){
tmp = q;
q->val += c;
c = q->val / 10;
q->val %= 10;
q = q->next;
}
if(c) {
ListNode * x = new ListNode(c, NULL);
tmp->next = x;
}
tmp = reverse(tmp2);
tmp2 = reverse(tmp);
return tmp2;
}
ListNode* reverse(ListNode* l1){
ListNode* p, *q, *tmp;
p = l1 ->next;
q = l1;
q->next = NULL;
while(p != NULL){
tmp = p->next;
p->next = q;
q = p;
p = tmp;
}
return q;
}
};