diff options
Diffstat (limited to 'content/datastructures')
| -rw-r--r-- | content/datastructures/monotonicConvexHull.cpp | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/content/datastructures/monotonicConvexHull.cpp b/content/datastructures/monotonicConvexHull.cpp index 44bff83..119015e 100644 --- a/content/datastructures/monotonicConvexHull.cpp +++ b/content/datastructures/monotonicConvexHull.cpp @@ -1,27 +1,27 @@ -// Lower Envelope mit MONOTONEN Inserts und Queries. Jede neue +// Lower Envelope mit MONOTONEN Inserts UND Queries. Jede neue // Gerade hat kleinere Steigung als alle vorherigen. struct Line { - ll m, b; - ll operator()(ll x) {return m*x+b;} + ll m, c; + ll operator()(ll x) {return m*x+c;} }; vector<Line> ls; -int ptr = 0; +ll ptr = 0; bool bad(Line l1, Line l2, Line l3) { - return (l3.b-l1.b)*(l1.m-l2.m) < (l2.b-l1.b)*(l1.m-l3.m); + return (l3.c-l1.c)*(l1.m-l2.m) < (l2.c-l1.c)*(l1.m-l3.m); } -void add(ll m, ll b) { // Laufzeit O(1) amortisiert - while (sz(ls) > 1 && bad(ls.end()[-2], ls.end()[-1], {m, b})) { +void add(ll m, ll c) { // Laufzeit O(1) amortisiert + while (sz(ls) > 1 && bad(ls.end()[-2], ls.end()[-1], {m, c})) { ls.pop_back(); } - ls.push_back({m, b}); + ls.push_back({m, c}); ptr = min(ptr, sz(ls) - 1); } ll query(ll x) { // Laufzeit: O(1) amortisiert ptr = min(ptr, sz(ls) - 1); - while (ptr < sz(ls)-1 && ls[ptr + 1](x) < ls[ptr](x)) ptr++; + while (ptr + 1 < sz(ls) && ls[ptr + 1](x) < ls[ptr](x)) ptr++; return ls[ptr](x); }
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