leetcode

5 Random Problems

6 files changed, 179 insertions(+), 0 deletions(-)

diff --git a/ Problems/0065.cpp b/ Problems/0065.cpp

@@ -0,0 +1,49 @@

class Solution {

using it_t = string::const_iterator;

static bool validSign(it_t &pos, const it_t &end) {

if (*pos == '-' || *pos == '+') {

pos++;

if (find(pos, end, '-') != end || find(pos, end, '+') != end) {

return false;

}

}

return pos != end;

}

static bool validDigit(const it_t &pos, const it_t &end) {

return all_of(pos, end, [](char c) { return isdigit(c); });

}

static bool isDecimal(const string &s) {

auto pos = begin(s);

if (!validSign(pos, end(s))) return false;

if (string(pos, end(s)) == ".") return false;

auto dot = find(pos, end(s), '.');

return validDigit(pos, dot) && validDigit(dot + 1, end(s));

}

static bool isInteger(const string &s) {

auto pos = begin(s);

if (!validSign(pos, end(s))) return false;

return validDigit(pos, end(s));

}

public:

bool isNumber(const string &s) const {

auto e = s.find('e'), E = s.find('E');

if (E != string::npos) swap(e, E);

if (e != string::npos) {

const string first = s.substr(0, e);

const string second = s.substr(e + 1);

return !first.empty() && !second.empty() && isInteger(second) &&

(isDecimal(first) || isInteger(first));

}

return isDecimal(s) || isInteger(s);

}

};

diff --git a/ Problems/0115.cpp b/ Problems/0115.cpp

@@ -0,0 +1,21 @@

class Solution {

static int dp[1001][1001];

static int rec(const string &s, const string &t, int check, int goal) {

if (goal == size(t)) return 1;

if (check == size(s)) return 0;

if (dp[check][goal] != -1) return dp[check][goal];

int res = rec(s, t, check + 1, goal);

if (s[check] == t[goal]) res += rec(s, t, check + 1, goal + 1);

return dp[check][goal] = res;

}

public:

int numDistinct(const string &s, const string &t) const {

memset(dp, 0xFF, sizeof(dp));

return rec(s, t, 0, 0);

}

};

int Solution::dp[1001][1001];

diff --git a/ Problems/0126.cpp b/ Problems/0126.cpp

@@ -0,0 +1,61 @@

class Solution {

unordered_map<string, vector<string>> adj;

vector<vector<string>> res;

vector<string> state;

void dfs(const string &crnt, int lvl) {

if (lvl == 0) {

res.push_back(state);

return;

}

for (const auto &word : adj[crnt]) {

state[lvl - 1] = word;

dfs(word, lvl - 1);

}

}

public:

vector<vector<string>> findLadders(const string &beginWord, const string &endWord,

vector<string> &wordList) {

unordered_set<string> set(begin(wordList), end(wordList));

unordered_set<string> seen;

queue<string> q;

q.push(beginWord);

for (int lvl = 1; !q.empty(); lvl++) {

for (int k = size(q); k > 0; k--) {

const auto root = q.front();

q.pop();

cout << root << endl;

if (root == endWord) {

state = vector<string>(lvl);

state[lvl - 1] = endWord;

dfs(root, lvl - 1);

return res;

}

auto crnt = root;

for (int i = 0; i < size(crnt); i++) {

const char og = crnt[i];

for (char c = 'a'; c <= 'z'; c++) {

crnt[i] = c;

if (!set.count(crnt)) continue;

if (!seen.count(crnt)) {

seen.emplace(crnt);

q.push(crnt);

}

adj[crnt].push_back(root);

}

crnt[i] = og;

}

}

for (const auto &word : seen)

set.erase(word);

}

return {};

}

};

diff --git a/ Problems/0132.cpp b/ Problems/0132.cpp

@@ -0,0 +1,22 @@

class Solution {

public:

int minCut(const string &s) const {

static bool dp[2001][2001];

static int cut[2001];

const int n = s.size();

memset(dp, 0x00, sizeof(dp));

for (int i = 0; i < n; i++) {

int mini = i;

for (int j = 0; j <= i; j++) {

if (s[i] == s[j] && (i - j < 3 || dp[i - 1][j + 1])) {

mini = j == 0 ? 0 : min(mini, cut[j - 1] + 1);

dp[i][j] = true;

}

}

cut[i] = mini;

}

return cut[n - 1];

}

};

diff --git a/ Problems/0147.cpp b/ Problems/0147.cpp

@@ -0,0 +1,21 @@

class Solution {

public:

ListNode *insertionSortList(ListNode *head) const {

ListNode dummy(-1, head);

ListNode *prev = &dummy, *crnt = head;

for (; crnt; prev = crnt, crnt = crnt->next) {

if (prev->val <= crnt->val) continue;

for (ListNode *p = &dummy, *c = dummy.next; p != prev; p = c, c = c->next) {

if (c->val <= crnt->val) continue;

prev->next = crnt->next;

crnt->next = p->next;

p->next = crnt;

crnt = prev;

break;

}

}

return dummy.next;

}

};

diff --git a/ README.md b/ README.md

@@ -88,6 +88,7 @@ for solving problems. | 0062 | Medium | [Unique Paths](Problems/0062.cpp) | | 0063 | Medium | [Unique Paths II](Problems/0063.cpp) | | 0064 | Medium | [Minimum Path Sum](Problems/0064.cpp) |

| 0065 | Hard | [Valid Number](Problems/0065.cpp) |

| 0066 | Easy | [Plus One](Problems/0066.cpp) | | 0067 | Easy | [Add Binary](Problems/0067.cpp) | | 0068 | Hard | [Text Justification](Problems/0068.cpp) |

@@ -137,6 +138,7 @@ for solving problems. | 0112 | Easy | [Path Sum](Problems/0112.cpp) | | 0113 | Medium | [Path Sum II](Problems/0113.cpp) | | 0114 | Medium | [Flatten Binary Tree to Linked List](Problems/0114.cpp) |

| 0115 | Hard | [Distinct Subsequences](Problems/0115.cpp) |

| 0116 | Medium | [Populating Next Right Pointers in Each Node](Problems/0116.cpp) | | 0117 | Medium | [Populating Next Right Pointers in Each Node II](Problems/0117.cpp) | | 0118 | Easy | [Pascal's Triangle](Problems/0118.cpp) |

@@ -147,11 +149,13 @@ for solving problems. | 0123 | Hard | [Best Time to Buy and Sell Stock III](Problems/0123.cpp) | | 0124 | Hard | [Binary Tree Maximum Path Sum](Problems/0124.cpp) | | 0125 | Easy | [Valid Palindrome](Problems/0125.cpp) |

| 0126 | Hard | [Word Ladder II](Problems/0126.cpp) |

| 0127 | Hard | [Word Ladder](Problems/0127.cpp) | | 0128 | Medium | [Longest Consecutive Sequence](Problems/0128.cpp) | | 0129 | Medium | [Sum Root to Leaf Numbers](Problems/0129.cpp) | | 0130 | Medium | [Surrounded Regions](Problems/0130.cpp) | | 0131 | Medium | [Palindrome Partitioning](Problems/0131.cpp) |

| 0132 | Hard | [Palindrome Partitioning II](Problems/0132.cpp) |

| 0133 | Medium | [Clone Graph](Problems/0133.cpp) | | 0134 | Medium | [Gas Station](Problems/0134.cpp) | | 0135 | Hard | [Candy](Problems/0135.cpp) |

@@ -166,6 +170,7 @@ for solving problems. | 0144 | Medium | [Binary Tree Preorder Traversal](Problems/0144.cpp) | | 0145 | Easy | [Binary Tree Postorder Traversal](Problems/0145.cpp) | | 0146 | Medium | [LRU Cache](Problems/0146.cpp) |

| 0147 | Medium | [Insertion Sort List](Problems/0147.cpp) |

| 0148 | Medium | [Sort List](Problems/0148.cpp) | | 0149 | Hard | [Max Points on a Line](Problems/0149.cpp) | | 0150 | Medium | [Evaluate Reverse Polish Notation](Problems/0150.cpp) |