leetcode

Daily Problem and 5 Random Problems

7 files changed, 166 insertions(+), 0 deletions(-)

diff --git a/ Problems/0341.cpp b/ Problems/0341.cpp

@@ -0,0 +1,24 @@

class NestedIterator {

stack<pair<vector<NestedInteger> *, int>> st;

public:

NestedIterator(vector<NestedInteger> &nestedList) { st.push({&nestedList, 0}); }

int next() {

if (!hasNext()) return -1;

auto &elem = st.top();

return (*elem.first)[elem.second++].getInteger();

}

bool hasNext() {

while (!st.empty()) {

auto &elem = st.top();

if (elem.second == elem.first->size()) {

st.pop();

continue;

}

if ((*elem.first)[elem.second].isInteger()) return true;

st.push({&(*elem.first)[elem.second++].getList(), 0});

}

return false;

}

};

diff --git a/ Problems/0386.cpp b/ Problems/0386.cpp

@@ -0,0 +1,19 @@

class Solution {

public:

vector<int> lexicalOrder(int n) {

vector<int> res(n);

int cur = 1;

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

res[i] = cur;

if (cur * 10 <= n)

cur *= 10;

else {

if (cur >= n) cur /= 10;

cur += 1;

while (cur % 10 == 0)

cur /= 10;

}

}

return res;

}

};

diff --git a/ Problems/0398.cpp b/ Problems/0398.cpp

@@ -0,0 +1,36 @@

#pragma GCC optimize("fast")

static auto _ = []() {

ios_base::sync_with_stdio(false);

cin.tie(NULL), cout.tie(NULL);

return 0;

}();

// O(n) pick, O(1) space

class Solution {

const vector<int> &nums;

public:

Solution(const vector<int> &nums) : nums(nums) {}

int pick(int target) {

int n = 0, ans = -1;

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

if (nums[i] != target) continue;

if (rand() % ++n == 0) ans = i;

}

return ans;

}

};

// O(1) pick, O(n) space

class Solution {

unordered_map<int, vector<int>> um;

public:

Solution(const vector<int> &nums) {

for (int i = 0; i < nums.size(); i++)

um[nums[i]].push_back(i);

}

int pick(int target) { return um[target][rand() % um[target].size()]; }

};

diff --git a/ Problems/1048.cpp b/ Problems/1048.cpp

@@ -0,0 +1,30 @@

class Solution {

public:

int longestStrChain(vector<string> &words) {

sort(begin(words), end(words), [](const auto &a, const auto &b) { return a.size() < b.size(); });

static int dp[1001];

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

int res = 0;

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

for (int j = i + 1; j < words.size(); j++) {

if (words[j].size() == words[i].size()) continue;

if (words[j].size() - words[i].size() > 1) break;

int k = 0, l = 0, diff = 0;

while (k < words[i].size()) {

if (words[i][k] == words[j][l])

k++, l++;

else {

l++;

if (diff++) break;

}

}

if (diff == 2) continue;

res = max(res, dp[j] = max(dp[j], dp[i] + 1));

}

}

return res + 1;

}

};

diff --git a/ Problems/1324.cpp b/ Problems/1324.cpp

@@ -0,0 +1,24 @@

class Solution {

public:

vector<string> printVertically(const string &s) {

vector<string> vec, res;

string tmp, buf;

stringstream ss(s);

while (ss >> tmp)

vec.push_back(tmp);

for (int i = 0; true; i++) {

tmp.clear(), buf.clear();

for (const string &s : vec) {

if (s.size() <= i)

buf += " ";

else

tmp += buf + s[i], buf.clear();

}

if (!tmp.size()) break;

res.push_back(tmp);

}

return res;

}

};

diff --git a/ Problems/1400.cpp b/ Problems/1400.cpp

@@ -0,0 +1,27 @@

class Solution {

public:

bool canConstruct(const string &s, int k) {

if (s.size() < k) return false;

int count[27] = {0};

for (const char c : s)

count[c & 0x1F]++;

int singles = 0;

for (int i = 1; i <= 26; i++)

singles += count[i] & 1;

return singles <= k;

}

};

class Solution {

public:

bool canConstruct(const string &s, int k) {

if (s.size() < k) return false;

bitset<27> bs;

for (const char c : s)

bs.flip(c & 0x1F);

return bs.count() <= k;

}

};

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

@@ -249,6 +249,7 @@ for solving problems. | 0332 | Hard | [Reconstruct Itinerary](Problems/0332.cpp) | | 0334 | Medium | [Increasing Triplet Subsequence](Problems/0334.cpp) | | 0338 | Easy | [Counting Bits](Problems/0338.cpp) |

| 0341 | Medium | [Flatten Nested List Iterator](Problems/0341.cpp) |

| 0342 | Easy | [Power of Four](Problems/0342.cpp) | | 0343 | Medium | [Integer Break](Problems/0343.cpp) | | 0344 | Easy | [Reverse String](Problems/0344.cpp) |

@@ -265,9 +266,11 @@ for solving problems. | 0382 | Medium | [Linked List Random Node](Problems/0382.cpp) | | 0383 | Easy | [Ransom Note](Problems/0383.cpp) | | 0384 | Medium | [Shuffle an Array](Problems/0384.cpp) |

| 0386 | Medium | [Lexicographical Numbers](Problems/0386.cpp) |

| 0387 | Easy | [First Unique Character in a String](Problems/0387.cpp) | | 0392 | Easy | [Is Subsequence](Problems/0392.cpp) | | 0394 | Medium | [Decode String](Problems/0394.cpp) |

| 0398 | Medium | [Random Pick Index](Problems/0398.cpp) |

| 0399 | Medium | [Evaluate Division](Problems/0399.cpp) | | 0402 | Medium | [Remove K Digits](Problems/0402.cpp) | | 0403 | Hard | [Frog Jump](Problems/0403.cpp) |

@@ -487,6 +490,7 @@ for solving problems. | 1043 | Medium | [Partition Array for Maximum Sum](Problems/1043.cpp) | | 1046 | Easy | [Last Stone Weight](Problems/1046.cpp) | | 1047 | Easy | [Remove All Adjacent Duplicates In String](Problems/1047.cpp) |

| 1048 | Medium | [Longest String Chain](Problems/1048.cpp) |

| 1051 | Easy | [Height Checker](Problems/1051.cpp) | | 1061 | Medium | [Lexicographically Smallest Equivalent String](Problems/1061.cpp) | | 1071 | Easy | [Greatest Common Divisor of Strings](Problems/1071.cpp) |

@@ -543,6 +547,7 @@ for solving problems. | 1318 | Medium | [Minimum Flips to Make a OR b Equal to c](Problems/1318.cpp) | | 1319 | Medium | [Number of Operations to Make Network Connected](Problems/1319.cpp) | | 1323 | Easy | [Maximum 69 Number](Problems/1323.cpp) |

| 1324 | Medium | [Print Words Vertically](Problems/1324.cpp) |

| 1325 | Medium | [Delete Leaves With a Given Value](Problems/1325.cpp) | | 1326 | Hard | [Minimum Number of Taps to Open to Water a Garden](Problems/1326.cpp) | | 1329 | Medium | [Sort the Matrix Diagonally](Problems/1329.cpp) |

@@ -573,6 +578,7 @@ for solving problems. | 1387 | Medium | [Sort Integers by The Power Value](Problems/1387.cpp) | | 1395 | Medium | [Count Number of Teams](Problems/1395.cpp) | | 1396 | Medium | [Design Underground System](Problems/1396.cpp) |

| 1400 | Medium | [Construct K Palindrome Strings](Problems/1400.cpp) |

| 1402 | Hard | [Reducing Dishes](Problems/1402.cpp) | | 1406 | Hard | [Stone Game III](Problems/1406.cpp) | | 1409 | Medium | [Queries on a Permutation With Key](Problems/1409.cpp) |