From bef2be80e88eb2192952364790a7f1c92738e898 Mon Sep 17 00:00:00 2001
From: Bruno Freitas Tissei <bft15@inf.ufpr.br>
Date: Wed, 13 Feb 2019 16:21:08 -0200
Subject: [PATCH] Small fixes
Signed-off-by: Bruno Freitas Tissei <bft15@inf.ufpr.br>
---
graph/lca.cpp | 2 ++
graph/tarjan.cpp | 2 +-
graph/topological_sort.cpp | 2 +-
math/modular_multiplicative_inverse.cpp | 4 ++--
paradigm/kadane.cpp | 7 ++++++-
string/kmp.cpp | 2 +-
structure/bit.cpp | 2 +-
structure/bit2d.cpp | 2 +-
structure/disjoint_set.cpp | 15 +++++++--------
structure/policy_tree.cpp | 2 ++
10 files changed, 24 insertions(+), 16 deletions(-)
diff --git a/graph/lca.cpp b/graph/lca.cpp
index 77b874c..5f43a33 100644
--- a/graph/lca.cpp
+++ b/graph/lca.cpp
@@ -11,6 +11,8 @@
* *** = used in both * and **
*/
+#define MAXLOG 20 //log2(MAX)
+
vector<int> graph[MAX]; //*** vector<ii>
int h[MAX];
diff --git a/graph/tarjan.cpp b/graph/tarjan.cpp
index f9e1952..bfcccdc 100644
--- a/graph/tarjan.cpp
+++ b/graph/tarjan.cpp
@@ -13,7 +13,7 @@ int ncomp, ind;
int cont[MAX], parent[MAX];
int low[MAX], L[MAX];
-// Fills scc with strongly connected components of graph
+// Fills SCC with strongly connected components of graph
void dfs(int x) {
L[x] = ind;
low[x] = ind++;
diff --git a/graph/topological_sort.cpp b/graph/topological_sort.cpp
index d5b6739..b4a7169 100644
--- a/graph/topological_sort.cpp
+++ b/graph/topological_sort.cpp
@@ -28,7 +28,7 @@ bool dfs(int x) {
}
-// Returns if graph contains cycle or not, and fills tsort vector with
+// Returns whether graph contains cycle or not, and fills tsort vector with
// topological sort of the graph
bool topological_sort(int n, vector<int> &tsort) {
mset(cont, 0);
diff --git a/math/modular_multiplicative_inverse.cpp b/math/modular_multiplicative_inverse.cpp
index ad96524..8a05798 100644
--- a/math/modular_multiplicative_inverse.cpp
+++ b/math/modular_multiplicative_inverse.cpp
@@ -6,7 +6,7 @@
*/
// ========== Fermat's Little Theorem ==========
-// Used if m is prime
+// Used when m is prime
ll power(ll x, ll y) {
ll ans = 1;
@@ -31,7 +31,7 @@ ll mod_inverse(ll a) {
// ========== Extended Euclidean Algorithm ==========
-// Used if m and a are coprime
+// Used when m and a are coprime
// return gcd(a, b) and find x, y where:
// a*x + b*y = gcd(a, b)
diff --git a/paradigm/kadane.cpp b/paradigm/kadane.cpp
index 8ad7c71..46d5b4e 100644
--- a/paradigm/kadane.cpp
+++ b/paradigm/kadane.cpp
@@ -1,5 +1,5 @@
/**
- * Kadane
+ * Kadane - Largest Sum Contiguous Subarray
*
* Complexity (Time): O(n + m)
* Complexity (Space): O(n + m)
@@ -8,6 +8,7 @@
int v[MAX];
int kadane() {
+
// Maximum so far (msf), Maximum ending here (meh).
int msf = -0x3f3f3f3f, meh = 0;
int start = 0, end = 0, s = 0;
@@ -15,12 +16,16 @@ int kadane() {
for (int i = 0; i < n; ++i) {
meh += v[i];
+ // Store maximum so far as well as starting and ending position
+ // of the subsequence
if (msf < meh) {
msf = meh;
start = s;
end = i;
}
+ // If maximum ending here is negative, then it's definitely
+ // better to restart
if (meh < 0) {
meh = 0;
s = i + 1;
diff --git a/string/kmp.cpp b/string/kmp.cpp
index 81fe7bd..741289a 100644
--- a/string/kmp.cpp
+++ b/string/kmp.cpp
@@ -1,5 +1,5 @@
/**
- * Knuth-Morris-Pratt - KMP
+ * Knuth-Morris-Pratt (KMP)
*
* Complexity (Time):
* preprocess -> O(m)
diff --git a/structure/bit.cpp b/structure/bit.cpp
index e42f305..69d3ab1 100644
--- a/structure/bit.cpp
+++ b/structure/bit.cpp
@@ -1,5 +1,5 @@
/**
- * Binary Indexed Tree - BIT
+ * Binary Indexed Tree (BIT)
*
* Complexity (Time):
* Update -> O(log n)
diff --git a/structure/bit2d.cpp b/structure/bit2d.cpp
index 63f3460..786faaa 100644
--- a/structure/bit2d.cpp
+++ b/structure/bit2d.cpp
@@ -1,5 +1,5 @@
/**
- * Binary Indexed Tree 2D - BIT2D
+ * Binary Indexed Tree 2D (BIT2D)
*
* Complexity (Time):
* Update -> O(log^2 n)
diff --git a/structure/disjoint_set.cpp b/structure/disjoint_set.cpp
index 22081e0..e8ebabe 100644
--- a/structure/disjoint_set.cpp
+++ b/structure/disjoint_set.cpp
@@ -10,13 +10,13 @@
int par[MAX];
int h[MAX];
-int sz[MAX];
+int size[MAX];
// Initialize element x
void make_set(int x) {
par[x] = x;
h[x] = 0;
- sz[x] = 1;
+ size[x] = 1;
}
@@ -39,13 +39,12 @@ void union_set(int x, int y) {
if (h[xroot] < h[yroot]) {
par[xroot] = yroot;
- sz[yroot] += sz[xroot];
- } else if (h[xroot] > h[yroot]) {
- par[yroot] = xroot;
- sz[xroot] += sz[yroot];
+ size[yroot] += size[xroot];
} else {
par[yroot] = xroot;
- sz[xroot] += sz[yroot];
- h[xroot]++;
+ size[xroot] += size[yroot];
+
+ if (h[xroot] == h[yroot])
+ h[xroot]++;
}
}
diff --git a/structure/policy_tree.cpp b/structure/policy_tree.cpp
index d93aca4..ee6cff3 100644
--- a/structure/policy_tree.cpp
+++ b/structure/policy_tree.cpp
@@ -1,6 +1,8 @@
/**
* Policy Tree
*
+ * A set-like STL structure with order statistics
+ *
* Complexity (Time):
* insert -> O(log n)
* erase -> O(log n)
--
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