leetcode

Solution to some Leetcode problems written in C++
git clone git://git.dimitrijedobrota.com/leetcode.git
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commit11516e28020baf08caeb9f312c286adaf0cfeb68
parent3fa12cfdd2b561baa15de38dfaed99e72d982c19
authorDimitrije Dobrota <mail@dimitrijedobrota.com>
dateSun, 30 Apr 2023 10:29:14 +0200

Daily Problem

Diffstat:
AProblems/1579.cpp|++++++++++++++++++++++++++++++++++++++++++++++++++++++++
MREADME.md|+
MTemplates/Union_Find.cpp|+++

3 files changed, 60 insertions(+), 0 deletions(-)

diff --git a/Problems/1579.cpp b/Problems/1579.cpp

@@ -0,0 +1,56 @@

class UnionFind {
int n, cnt = n;
vector<int> root, size;
public:
UnionFind(int n) : n(n), root(n), size(n, 1) {
iota(root.begin(), root.end(), 0);
}
UnionFind(const UnionFind &uf)
: n(uf.n), cnt(uf.cnt), root(uf.root), size(uf.size) {}
static int redundant;
int find(int x) {
while (x != root[x]) x = root[x] = root[root[x]];
return x;
}
void join(int x, int y) {
x = find(x), y = find(y);
if (x != y) {
if (size[x] > size[y]) swap(x, y);
root[x] = y;
size[y] += size[x];
cnt--;
} else
redundant++;
}
int count() { return cnt; }
bool connected(int x, int y) { return find(x) == find(y); }
};
int UnionFind::redundant = 0;
class Solution {
public:
int maxNumEdgesToRemove(int n, vector<vector<int>> &e) {
UnionFind::redundant = 0;
UnionFind a(n + 1);
for (int i = 0; i < e.size(); i++)
if (e[i][0] == 3) a.join(e[i][1], e[i][2]);
UnionFind b = a;
for (int i = 0; i < e.size(); i++)
if (e[i][0] == 1)
a.join(e[i][1], e[i][2]);
else if (e[i][0] == 2)
b.join(e[i][1], e[i][2]);
// count must be 2, since 0 is not used
return a.count() == 2 && b.count() == 2 ? UnionFind::redundant : -1;
}
};

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

@@ -455,6 +455,7 @@ for solving problems.

| 1544 | Easy | [Make The String Great](Problems/1544.cpp) |
| 1557 | Medium | [Minimum Number of Vertices to Reach All Nodes](Problems/1557.cpp) |
| 1567 | Medium | [Maximum Length of Subarray With Positive Product](Problems/1567.cpp) |
| 1579 | Hard | [Remove Max Number of Edges to Keep Graph Fully Traversable](Problems/1579.cpp) |
| 1584 | Medium | [Min Cost to Connect All Points](Problems/1584.cpp) |
| 1609 | Medium | [Even Odd Tree](Problems/1609.cpp) |
| 1615 | Medium | [Maximal Network Rank](Problems/1615.cpp) |

diff --git a/Templates/Union_Find.cpp b/Templates/Union_Find.cpp

@@ -7,6 +7,9 @@ public:

iota(root.begin(), root.end(), 0);
}
UnionFind(const UnionFind &uf)
: n(uf.n), cnt(uf.cnt), root(uf.root), size(uf.size) {}
int find(int x) {
while (x != root[x]) x = root[x] = root[root[x]];
return x;