leetcode

Solution to some Leetcode problems written in C++
git clone git://git.dimitrijedobrota.com/leetcode.git
Log | Files | Refs | README | LICENSE |
commit5b4835a538e3d35db93d58b64e4e3b8bdf58affc
parentf5a7b3222c3e691e5f16f087dfea040e10a0c14d
authorDimitrije Dobrota <mail@dimitrijedobrota.com>
dateThu, 29 Jun 2023 16:35:18 +0200

Daily Problem

Diffstat:
AProblems/0846.cpp|+++++++++++++++++++++++++++++++++++++++++++++++++++++++
MREADME.md|+

2 files changed, 56 insertions(+), 0 deletions(-)

diff --git a/Problems/0846.cpp b/Problems/0846.cpp

@@ -0,0 +1,55 @@

class Solution {
typedef tuple<int, int, char> record;
int cantor(int a, int b) { return (a + b + 1) * (a + b) / 2 + b; }
int hash(const record &r) {
return cantor(get<0>(r), cantor(get<1>(r), get<2>(r)));
}
int n, m;
int valid(int x, int y) { return x >= 0 && y >= 0 && x < n && y < m; }
public:
int shortestPathAllKeys(const vector<string> &grid) {
static const int offset_x[] = {0, 0, 1, -1};
static const int offset_y[] = {1, -1, 0, 0};
n = grid.size(), m = grid[0].size();
int start_x = -1, start_y = -1, goal = 0;
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
if (grid[i][j] == '@')
start_x = i, start_y = j;
else if (islower(grid[i][j]))
goal |= 1 << (grid[i][j] & 0xF);
}
}
unordered_set<int> visited;
queue<record> q;
q.push({start_x, start_y, 0});
visited.insert(hash(q.front()));
for (int step = 0; !q.empty(); step++) {
for (int k = q.size(); k > 0; k--) {
auto [x, y, keys] = q.front();
q.pop();
if (keys == goal) return step;
for (int k = 0; k < 4; k++) {
int i = x + offset_x[k], j = y + offset_y[k], key = keys;
if (!valid(i, j) || grid[i][j] == '#') continue;
if (isupper(grid[i][j]) && !(key & (1 << (grid[i][j] & 0xF))))
continue;
if (islower(grid[i][j])) key |= 1 << (grid[i][j] & 0xF);
const record r = {i, j, key};
if (!visited.count(hash(r))) {
visited.insert(hash(r));
q.push(r);
}
}
}
}
return -1;
}
};

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

@@ -360,6 +360,7 @@ for solving problems.

| 0844 | Easy | [Backspace String Compare](Problems/0844.cpp) |
| 0851 | Medium | [Loud and Rich](Problems/0851.cpp) |
| 0853 | Medium | [Car Fleet](Problems/0853.cpp) |
| 0864 | Medium | [Shortest Path to Get All Keys](Problems/0864.cpp) |
| 0872 | Easy | [Leaf-Similar Trees](Problems/0872.cpp) |
| 0875 | Medium | [Koko Eating Bananas](Problems/0875.cpp) |
| 0876 | Easy | [Middle of the Linked List](Problems/0876.cpp) |