leetcode

Solution to some Leetcode problems written in C++
git clone git://git.dimitrijedobrota.com/leetcode.git
Log | Files | Refs | README | LICENSE |
commitd9c665c3d6886216c99798d8c52099ff781b5a71
parent938b692ac94451317ef6757e57f8653fc0de6772
authorDimitrije Dobrota <mail@dimitrijedobrota.com>
dateSat, 7 Jan 2023 14:47:07 +0100

Daily problem + one hard

Diffstat:
AProblems/0134.cpp|+++++++++++++++
AProblems/0135.cpp|+++++++++++++++++++++++++++++++++++++++++++++++
MREADME.md|++

3 files changed, 64 insertions(+), 0 deletions(-)

diff --git a/Problems/0134.cpp b/Problems/0134.cpp

@@ -0,0 +1,15 @@

class Solution {
public:
int canCompleteCircuit(vector<int> &gas, vector<int> &cost) {
int start = 0, total = 0, tank = 0;
for (int i = 0; i < gas.size(); i++) {
tank = tank + gas[i] - cost[i];
if (tank < 0) {
start = i + 1;
total += tank;
tank = 0;
}
}
return (total + tank >= 0) ? start : -1;
}
};

diff --git a/Problems/0135.cpp b/Problems/0135.cpp

@@ -0,0 +1,47 @@

// original solution - accepted
class Solution {
public:
int candy(vector<int> &ratings) {
// place holder rating for easy neighbor calculation
ratings.insert(ratings.begin(), -1), ratings.push_back(-1);
int n = ratings.size();
// sort by rating remembering the original index
vector<pair<int, int>> vec;
vec.reserve(n);
for (int i = 1; i < n - 1; i++) vec.push_back({ratings[i], i});
sort(vec.begin(), vec.end());
vector<int> res(n, 1); // 'Each child must have at least one candy'
res.front() = res.back() = 0; // except placeholders
for (auto &[rating, index] : vec) {
if (rating < ratings[index + 1])
res[index + 1] = max(res[index + 1], res[index] + 1);
if (rating < ratings[index - 1])
res[index - 1] = max(res[index - 1], res[index] + 1);
}
return accumulate(res.begin(), res.end(), 0);
}
};
// improved solution - same logic no nonsense
class Solution {
public:
int candy(vector<int> &ratings) {
int n = ratings.size();
if (n <= 1) return n;
vector<int> res(n, 1);
for (int i = 0; i < n - 1; i++) {
if (ratings[i] < ratings[i + 1]) res[i + 1] = res[i] + 1;
}
for (int i = n - 1; i > 0; i--) {
if (ratings[i] < ratings[i - 1]) res[i - 1] = max(res[i - 1], res[i] + 1);
}
return accumulate(res.begin(), res.end(), 0);
}
};

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

@@ -76,6 +76,8 @@ for solving problems.

| 0125 | Easy | [Valid Palindrome](Problems/0125.cpp) |
| 0129 | Medium | [Sum Root to Leaf Numbers](Problems/0129.cpp) |
| 0133 | Medium | [Clone Graph](Problems/0133.cpp) |
| 0134 | Medium | [Gas Station](Problems/0134.cpp) |
| 0135 | Hard | [Candy](Problems/0135.cpp) |
| 0138 | Medium | [Copy List with Random Pointer](Problems/0138.cpp) |
| 0141 | Easy | [Linked List Cycle](Problems/0141.cpp) |
| 0142 | Medium | [Linked List Cycle II](Problems/0142.cpp) |