• CF280D k-Maximum Subsequence Sum(线段树)

    在做这题时我一开始把(tag)写入了结构体

    #include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <cmath>
#define R(a,b,c) for(register int a = (b); a <= (c); ++a)
#define nR(a,b,c) for(register int a = (b); a >= (c); --a)
#define Fill(a,b) memset(a, b, sizeof(a))
#define Swap(a,b) ((a) ^= (b) ^= (a) ^= (b))
#define QWQ
#ifdef QWQ
#define D_e_Line printf("
---------------
")
#define D_e(x) cout << (#x) << " : " << x << "
"
#define Pause() system("pause")
#define FileOpen() freopen("in.txt", "r", stdin)
#define FileSave() freopen("out.txt", "w", stdout)
#define TIME() fprintf(stderr, "
TIME : %.3lfms
", clock() * 1000.0 / CLOCKS_PER_SEC)
#else
#define D_e_Line ;
#define D_e(x) ;
#define Pause() ;
#define FileOpen() ;
#define FileSave() ;
#define TIME() ;
#endif
struct ios {
	template<typename ATP> inline ios& operator >> (ATP &x) {
		x = 0; int f = 1; char c;
		for(c = getchar(); c < '0' || c > '9'; c = getchar()) if(c == '-') f = -1;
		while(c >= '0' && c <='9') x = x * 10 + (c ^ '0'), c = getchar();
		x *= f;
		return *this;
	}
}io;
using namespace std;
template<typename ATP> inline ATP Max(ATP a, ATP b) {
	return a > b ? a : b;
}
template<typename ATP> inline ATP Min(ATP a, ATP b) {
	return a < b ? a : b;
}
template<typename ATP> inline ATP Abs(ATP a) {
	return a < 0 ? -a : a;
}

const int N = 1e5 + 7;

int n;

struct RPG {
	int l, r, sum;
	bool operator < (const RPG &com) const {
		return sum < com.sum;
	}
	RPG operator + (const RPG &b) const {
		return (RPG){ l, b.r, sum + b.sum};
	}
};
struct nod {
	RPG lmax, lmin, rmin, rmax, mx, mn, all;
	bool tag;!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	bool operator < (const nod &com) const {
		return mx.sum < com.mx.sum;
	}
} t[N << 2];
#define ls rt << 1
#define rs rt << 1 | 1
#define lson rt << 1, l, mid
#define rson rt << 1 | 1, mid + 1, r
inline void Newnode(int rt, int pos, int val) {
	t[rt].lmax = t[rt].lmin = t[rt].rmax = t[rt].rmin = t[rt].mx = t[rt].mn = t[rt].all = (RPG){ pos, pos, val};
}
inline nod Merge(nod x, nod y) {
	nod s;
	s.lmax = max(x.lmax, x.all + y.lmax);
	s.lmin = min(x.lmin, x.all + y.lmin);
	s.rmax = max(y.rmax, x.rmax + y.all);
	s.rmin = min(y.rmin, x.rmin + y.all);
	s.mx = max(max(x.mx, y.mx), x.rmax + y.lmax);
	s.mn = min(min(x.mn, y.mn), x.rmin + y.lmin);
	s.all = x.all + y.all;
	return s;
}
inline void Pushup(int &rt) {
	t[rt] = Merge(t[ls], t[rs]);
}
inline void Pushrev(int rt) {
	swap(t[rt].lmax, t[rt].lmin);
	swap(t[rt].rmax, t[rt].rmin);
	swap(t[rt].mx, t[rt].mn);
	t[rt].lmax.sum = -t[rt].lmax.sum;
	t[rt].lmin.sum = -t[rt].lmin.sum;
	t[rt].rmax.sum = -t[rt].rmax.sum;
	t[rt].rmin.sum = -t[rt].rmin.sum;
	t[rt].mx.sum = -t[rt].mx.sum;
	t[rt].mn.sum = -t[rt].mn.sum;
	t[rt].all.sum = -t[rt].all.sum;
	t[rt].tag ^= 1;//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
}
inline void Pushdown(int rt) {
	if(!t[rt].tag) return;//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	Pushrev(ls);
	Pushrev(rs);
	t[rt].tag = 0;//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
}
inline void Modify(int rt, int l, int r, int x, int w) {
	if(l == r){
		Newnode(rt, x, w);
		return;
	}
	Pushdown(rt);
	int mid = (l + r) >> 1;
	if(x <= mid)
		Modify(lson, x, w);
	else
		Modify(rson, x, w);
	Pushup(rt);
}
inline void Updata(int rt, int l, int r, int L, int R) {
	if(L <= l && r <= R){
		Pushrev(rt);
		return;
	}
	Pushdown(rt);
	int mid = (l + r) >> 1;
	if(L <= mid) Updata(lson, L, R);
	if(R > mid) Updata(rson, L, R);
	Pushup(rt);
	return;
}
inline nod Query(int rt, int l, int r, int L, int R) {
	if(L <= l && r <= R) return t[rt];
	Pushdown(rt);
	int mid = (l + r) >> 1;
	if(R <= mid) return Query(lson, L, R);
	else if(L > mid) return Query(rson, L, R);
	else return Merge(Query(lson, L, R), Query(rson, L, R));
	Pushup(rt);
}

nod sta[N];
int top;
inline int Solve(int l, int r, int K) {
	int ans = 0;
	while(K--){
		nod s = Query(1, 1, n, l, r);
		if(s.mx.sum < 0) break;
		ans += s.mx.sum;
		Updata(1, 1, n, s.mx.l, s.mx.r);
		sta[++top] = s;
	}
	while(top){
		nod s = sta[top--];
		Updata(1, 1, n, s.mx.l, s.mx.r);
	}
	return ans;
}

int main() {
//FileOpen();
	io >> n;
	R(i,1,n){
		int x;
		io >> x;
		Modify(1, 1, n, i, x);
	}
	
	int m;
	io >> m;
	while(m--){
		int opt;
		io >> opt;
		if(opt){
			int l, r, K;
			io >> l >> r >> K;
			printf("%d
", Solve(l, r, K));
		}
		else{
			int x, w;
			io >> x >> w;
			Modify(1, 1, n, x, w);
		}
	}
	
	return 0;
}

    (注意打感叹号处)

    一直没过样例，后来参考一位大佬的代码把(tag)单独放外面

    #include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <cmath>
#define R(a,b,c) for(register int a = (b); a <= (c); ++a)
#define nR(a,b,c) for(register int a = (b); a >= (c); --a)
#define Fill(a,b) memset(a, b, sizeof(a))
#define Swap(a,b) ((a) ^= (b) ^= (a) ^= (b))
#define QWQ
#ifdef QWQ
#define D_e_Line printf("
---------------
")
#define D_e(x) cout << (#x) << " : " << x << "
"
#define Pause() system("pause")
#define FileOpen() freopen("in.txt", "r", stdin)
#define FileSave() freopen("out.txt", "w", stdout)
#define TIME() fprintf(stderr, "
TIME : %.3lfms
", clock() * 1000.0 / CLOCKS_PER_SEC)
#else
#define D_e_Line ;
#define D_e(x) ;
#define Pause() ;
#define FileOpen() ;
#define FileSave() ;
#define TIME() ;
#endif
struct ios {
	template<typename ATP> inline ios& operator >> (ATP &x) {
		x = 0; int f = 1; char c;
		for(c = getchar(); c < '0' || c > '9'; c = getchar()) if(c == '-') f = -1;
		while(c >= '0' && c <='9') x = x * 10 + (c ^ '0'), c = getchar();
		x *= f;
		return *this;
	}
}io;
using namespace std;
template<typename ATP> inline ATP Max(ATP a, ATP b) {
	return a > b ? a : b;
}
template<typename ATP> inline ATP Min(ATP a, ATP b) {
	return a < b ? a : b;
}
template<typename ATP> inline ATP Abs(ATP a) {
	return a < 0 ? -a : a;
}

const int N = 1e5 + 7;

int n;

struct RPG {
	int l, r, sum;
	bool operator < (const RPG &com) const {
		return sum < com.sum;
	}
	RPG operator + (const RPG &b) const {
		return (RPG){ l, b.r, sum + b.sum};
	}
};
struct nod {
	RPG lmax, lmin, rmin, rmax, mx, mn, all;
	bool operator < (const nod &com) const {
		return mx.sum < com.mx.sum;
	}
} t[N << 2];
bool tag[N << 2]; //!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
#define ls rt << 1
#define rs rt << 1 | 1
#define lson rt << 1, l, mid
#define rson rt << 1 | 1, mid + 1, r
inline void Newnode(int rt, int pos, int val) {
	t[rt].lmax = t[rt].lmin = t[rt].rmax = t[rt].rmin = t[rt].mx = t[rt].mn = t[rt].all = (RPG){ pos, pos, val};
}
inline nod Merge(nod x, nod y) {
	nod s;
	s.lmax = max(x.lmax, x.all + y.lmax);
	s.lmin = min(x.lmin, x.all + y.lmin);
	s.rmax = max(y.rmax, x.rmax + y.all);
	s.rmin = min(y.rmin, x.rmin + y.all);
	s.mx = max(max(x.mx, y.mx), x.rmax + y.lmax);
	s.mn = min(min(x.mn, y.mn), x.rmin + y.lmin);
	s.all = x.all + y.all;
	return s;
}
inline void Pushup(int &rt) {
	t[rt] = Merge(t[ls], t[rs]);
}
inline void Pushrev(int rt) {
	swap(t[rt].lmax, t[rt].lmin);
	swap(t[rt].rmax, t[rt].rmin);
	swap(t[rt].mx, t[rt].mn);
	t[rt].lmax.sum = -t[rt].lmax.sum;
	t[rt].lmin.sum = -t[rt].lmin.sum;
	t[rt].rmax.sum = -t[rt].rmax.sum;
	t[rt].rmin.sum = -t[rt].rmin.sum;
	t[rt].mx.sum = -t[rt].mx.sum;
	t[rt].mn.sum = -t[rt].mn.sum;
	t[rt].all.sum = -t[rt].all.sum;
	tag[rt] ^= 1;//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
}
inline void Pushdown(int rt) {
	if(!tag[rt]) return;//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	Pushrev(ls);
	Pushrev(rs);
	tag[rt] = 0;//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
}
inline void Modify(int rt, int l, int r, int x, int w) {
	if(l == r){
		Newnode(rt, x, w);
		return;
	}
	Pushdown(rt);
	int mid = (l + r) >> 1;
	if(x <= mid)
		Modify(lson, x, w);
	else
		Modify(rson, x, w);
	Pushup(rt);
}
inline void Updata(int rt, int l, int r, int L, int R) {
	if(L <= l && r <= R){
		Pushrev(rt);
		return;
	}
	Pushdown(rt);
	int mid = (l + r) >> 1;
	if(L <= mid) Updata(lson, L, R);
	if(R > mid) Updata(rson, L, R);
	Pushup(rt);
	return;
}
inline nod Query(int rt, int l, int r, int L, int R) {
	if(L <= l && r <= R) return t[rt];
	Pushdown(rt);
	int mid = (l + r) >> 1;
	if(R <= mid) return Query(lson, L, R);
	else if(L > mid) return Query(rson, L, R);
	else return Merge(Query(lson, L, R), Query(rson, L, R));
	Pushup(rt);
}

nod sta[N];
int top;
inline int Solve(int l, int r, int K) {
	int ans = 0;
	while(K--){
		nod s = Query(1, 1, n, l, r);
		if(s.mx.sum < 0) break;
		ans += s.mx.sum;
		Updata(1, 1, n, s.mx.l, s.mx.r);
		sta[++top] = s;
	}
	while(top){
		nod s = sta[top--];
		Updata(1, 1, n, s.mx.l, s.mx.r);
	}
	return ans;
}

int main() {
//FileOpen();
	io >> n;
	R(i,1,n){
		int x;
		io >> x;
		Modify(1, 1, n, i, x);
	}
	
	int m;
	io >> m;
	while(m--){
		int opt;
		io >> opt;
		if(opt){
			int l, r, K;
			io >> l >> r >> K;
			printf("%d
", Solve(l, r, K));
		}
		else{
			int x, w;
			io >> x >> w;
			Modify(1, 1, n, x, w);
		}
	}
	
	return 0;
}

    (注意感叹号处)

    就成功过掉了

    这是为什么呢？是哪儿影响的呢？

    大佬发话
    原来是(Merge())处没有初始化！

    模拟费用流，线段树维护区间

    #include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <cmath>
#define R(a,b,c) for(register int a = (b); a <= (c); ++a)
#define nR(a,b,c) for(register int a = (b); a >= (c); --a)
#define Fill(a,b) memset(a, b, sizeof(a))
#define Swap(a,b) ((a) ^= (b) ^= (a) ^= (b))
#define QWQ
#ifdef QWQ
#define D_e_Line printf("
---------------
")
#define D_e(x) cout << (#x) << " : " << x << "
"
#define Pause() system("pause")
#define FileOpen() freopen("in.txt", "r", stdin)
#define FileSave() freopen("out.txt", "w", stdout)
#define TIME() fprintf(stderr, "
TIME : %.3lfms
", clock() * 1000.0 / CLOCKS_PER_SEC)
#else
#define D_e_Line ;
#define D_e(x) ;
#define Pause() ;
#define FileOpen() ;
#define FileSave() ;
#define TIME() ;
#endif
struct ios {
	template<typename ATP> inline ios& operator >> (ATP &x) {
		x = 0; int f = 1; char c;
		for(c = getchar(); c < '0' || c > '9'; c = getchar()) if(c == '-') f = -1;
		while(c >= '0' && c <='9') x = x * 10 + (c ^ '0'), c = getchar();
		x *= f;
		return *this;
	}
}io;
using namespace std;
template<typename ATP> inline ATP Max(ATP a, ATP b) {
	return a > b ? a : b;
}
template<typename ATP> inline ATP Min(ATP a, ATP b) {
	return a < b ? a : b;
}
template<typename ATP> inline ATP Abs(ATP a) {
	return a < 0 ? -a : a;
}

const int N = 1e5 + 7;

int n;

struct RPG {
	int l, r, sum;
	bool operator < (const RPG &com) const {
		return sum < com.sum;
	}
	RPG operator + (const RPG &b) const {
		return (RPG){ l, b.r, sum + b.sum};
	}
};
struct nod {
	RPG lmax, lmin, rmin, rmax, mx, mn, all;
	bool tag;//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	bool operator < (const nod &com) const {
		return mx.sum < com.mx.sum;
	}
} t[N << 2];
#define ls rt << 1
#define rs rt << 1 | 1
#define lson rt << 1, l, mid
#define rson rt << 1 | 1, mid + 1, r
inline void ChangeNode(int rt, int pos, int val) {
	t[rt].lmax = t[rt].lmin = t[rt].rmax = t[rt].rmin = t[rt].mx = t[rt].mn = t[rt].all = (RPG){ pos, pos, val};
}
inline nod Merge(nod x, nod y) {
	nod s;
	s.lmax = max(x.lmax, x.all + y.lmax);
	s.lmin = min(x.lmin, x.all + y.lmin);
	s.rmax = max(y.rmax, x.rmax + y.all);
	s.rmin = min(y.rmin, x.rmin + y.all);
	s.mx = max(max(x.mx, y.mx), x.rmax + y.lmax);
	s.mn = min(min(x.mn, y.mn), x.rmin + y.lmin);
	s.all = x.all + y.all;
	s.tag = false;
	return s;
}
inline void Pushup(int &rt) {
	t[rt] = Merge(t[ls], t[rs]);
}
inline void Pushrev(int rt) {
	swap(t[rt].lmax, t[rt].lmin);
	swap(t[rt].rmax, t[rt].rmin);
	swap(t[rt].mx, t[rt].mn);
	t[rt].lmax.sum = -t[rt].lmax.sum;
	t[rt].lmin.sum = -t[rt].lmin.sum;
	t[rt].rmax.sum = -t[rt].rmax.sum;
	t[rt].rmin.sum = -t[rt].rmin.sum;
	t[rt].mx.sum = -t[rt].mx.sum;
	t[rt].mn.sum = -t[rt].mn.sum;
	t[rt].all.sum = -t[rt].all.sum;
	t[rt].tag ^= 1;//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
}
inline void Pushdown(int rt) {
	if(!t[rt].tag) return;//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	Pushrev(ls);
	Pushrev(rs);
	t[rt].tag = 0;//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
}
inline void Modify(int rt, int l, int r, int x, int w) {
	if(l == r){
		ChangeNode(rt, x, w);
		return;
	}
	Pushdown(rt);
	int mid = (l + r) >> 1;
	if(x <= mid)
		Modify(lson, x, w);
	else
		Modify(rson, x, w);
	Pushup(rt);
}
inline void Updata(int rt, int l, int r, int L, int R) {
	if(L <= l && r <= R){
		Pushrev(rt);
		return;
	}
	Pushdown(rt);
	int mid = (l + r) >> 1;
	if(L <= mid) Updata(lson, L, R);
	if(R > mid) Updata(rson, L, R);
	Pushup(rt);
	return;
}
inline nod Query(int rt, int l, int r, int L, int R) {
	if(L <= l && r <= R) return t[rt];
	Pushdown(rt);
	int mid = (l + r) >> 1;
	if(R <= mid) return Query(lson, L, R);
	else if(L > mid) return Query(rson, L, R);
	else return Merge(Query(lson, L, R), Query(rson, L, R));
	Pushup(rt);
}

nod sta[N];
int top;
inline int Solve(int l, int r, int K) {
	int ans = 0;
	while(K--){
		nod s = Query(1, 1, n, l, r);
		if(s.mx.sum < 0) break;
		ans += s.mx.sum;
		Updata(1, 1, n, s.mx.l, s.mx.r);
		sta[++top] = s;
	}
	while(top){
		nod s = sta[top--];
		Updata(1, 1, n, s.mx.l, s.mx.r);
	}
	return ans;
}

int main() {
//FileOpen();
	io >> n;
	R(i,1,n){
		int x;
		io >> x;
		Modify(1, 1, n, i, x);
	}
	
	int m;
	io >> m;
	while(m--){
		int opt;
		io >> opt;
		if(opt){
			int l, r, K;
			io >> l >> r >> K;
			printf("%d
", Solve(l, r, K));
		}
		else{
			int x, w;
			io >> x >> w;
			Modify(1, 1, n, x, w);
		}
	}
	
	return 0;
}

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  • 原文地址：https://www.cnblogs.com/bingoyes/p/11740911.html
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