牛多校1I Points Division(DP)题解
Posted kirinsb
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题意:n个点,分成两组A,B,如果点i在A中,那么贡献值\(a_i\),反之为\(b_i\)。
现要求任意\(i \in A,j \in B\)不存在 \(x_i >= x_j\) 且 \(y_i <= y_j\),也就是说A中点不在B中点的右下方。
思路:https://blog.nowcoder.net/n/7205418146f3446eb0b1ecec8d2ab1da
代码:
#include<cmath>
#include<set>
#include<map>
#include<queue>
#include<cstdio>
#include<vector>
#include<cstring>
#include <iostream>
#include<algorithm>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
const int maxn = 1e5 + 5;
const int M = 50 + 5;
const ull seed = 131;
const int INF = 0x3f3f3f3f;
const int MOD = 1000000007;
struct Node
int x, y, a, b;
p[maxn];
bool cmp(Node x, Node y)
if(x.x == y.x) return x.y > y.y;
return x.x < y.x;
vector<int> vv;
ll Max[maxn << 2], lazy[maxn << 2];
void pushup(int rt)
Max[rt] = max(Max[rt << 1], Max[rt << 1 | 1]);
void pushdown(int rt)
if(lazy[rt])
lazy[rt << 1] += lazy[rt];
lazy[rt << 1 | 1] += lazy[rt];
Max[rt << 1] += lazy[rt];
Max[rt << 1 | 1] += lazy[rt];
lazy[rt] = 0;
void build(int l, int r, int rt)
Max[rt] = lazy[rt] = 0;
if(l == r) return;
int m = (l + r) >> 1;
build(l, m, rt << 1);
build(m + 1, r, rt << 1 | 1);
void update(int L, int R, int l, int r, int v, int rt)
if(L > R) return;
if(L <= l && R >= r)
Max[rt] += v;
lazy[rt] += v;
return;
pushdown(rt);
int m = (l + r) >> 1;
if(L <= m)
update(L, R, l, m, v, rt << 1);
if(R > m)
update(L, R, m + 1, r, v, rt << 1 | 1);
pushup(rt);
void change(int pos , int l, int r, ll v, int rt)
if(l == r)
Max[rt] = max(Max[rt], v);
return;
pushdown(rt);
int m = (l + r) >> 1;
if(pos <= m)
change(pos, l, m, v, rt << 1);
else
change(pos, m + 1, r, v, rt << 1 | 1);
pushup(rt);
ll query(int L, int R, int l, int r, int rt)
if(L <= l && R >= r)
return Max[rt];
pushdown(rt);
int m = (l + r) >> 1;
ll MAX = -1;
if(L <= m)
MAX = max(MAX, query(L, R, l, m, rt << 1));
if(R > m)
MAX = max(MAX, query(L, R, m + 1, r, rt << 1 | 1));
pushup(rt);
return MAX;
int main()
int n;
while(~scanf("%d", &n))
vv.clear();
for(int i = 1; i <= n; i++)
scanf("%d%d%d%d", &p[i].x, &p[i].y, &p[i].a, &p[i].b);
vv.push_back(p[i].y);
vv.push_back(-1);
sort(vv.begin(), vv.end());
vv.erase(unique(vv.begin(), vv.end()), vv.end());
for(int i = 1; i <= n; i++) p[i].y = lower_bound(vv.begin(), vv.end(), p[i].y) - vv.begin() + 1;
sort(p + 1, p + n + 1, cmp);
build(1, vv.size(), 1);
for(int i = 1; i <= n; i++)
ll tmp = query(1, p[i].y, 1, vv.size(), 1);
update(p[i].y, vv.size(), 1, vv.size(), p[i].b, 1);
update(1, p[i].y - 1, 1, vv.size(), p[i].a, 1);
change(p[i].y, 1, vv.size(), tmp + p[i].b, 1);
printf("%lld\n", Max[1]);
return 0;
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