导言
在一些毒瘤题中，不完全是正解 + 正常的输入输出是被卡常然后会 TLE 的。所以这些时候，就需要快读/快写了。
当然，快读/快写也可以帮你在比赛中多水一些分。
1.int && long long
inline int read() {
int x = 0, f = 1;
char ch = getchar();
while (ch < '0' || ch > '9') {
if (ch == '-') f = -1;
ch = getchar();
}
while (ch >= '0' && ch <= '9') {
x = (x << 1) + (x << 3) + (ch ^ 48);
ch = getchar();
}
return x * f;
}
inline void write(int x) {
if (x < 0) {
x = -x;
putchar('-');
}
if (x > 9) write(x / 10);
putchar(x % 10 + '0');
}
优化
不要忘记带上上面的读写
inline char getchar() {
if (p1 == p2) {
p1 = buf;
p2 = buf + fread(buf, 1, 1 << 20, stdin);
if (p1 == p2) return EOF;
else return *p1++;
}
return *p1++;
}
fread
namespace fastread {
const int S = 1 << 16;
char B[S + 3], *H, *T;
inline int gc() {
if (H == T) T = (H = B) + fread(B, 1, S, stdin);
return (H == T) ? EOF : *H++;
}
inline int read() {
int x, ch;
while ((ch = gc()) < 48);
x = ch^'0';
while ((ch = gc()) > 47) x = x * 10 + (ch^'0');
return x;
}
} using fastread::read;
namespace fastwrite {
const int S = 1 << 16;
int cnt;
char B[S + 3];
inline void write(int x) {
if (x > 9) write(x / 10);
B[cnt++] = (x % 10) | 48;
if (cnt == S) {
fwrite(B, 1, S, stdout);
cnt = 0;
}
}
inline void space() {
B[cnt++] = 32;
if (cnt == S) {
fwrite(B, 1, S, stdout);
cnt = 0;
}
}
inline void endl() {
B[cnt++] = 10;
if (cnt == S) {
fwrite(B, 1, S, stdout);
cnt = 0;
}
}
inline void show() {
fwrite(B, 1, cnt, stdout);
cnt = 0;
}
} using fastwrite::write, fastwrite::space, fastwrite::show;
更“实用”的
namespace fastIO {
#define BUF_SIZE 100000
//fread -> read
bool IOerror = 0;
inline char nc() {
static char buf[BUF_SIZE], *p1 = buf + BUF_SIZE, *pend = buf + BUF_SIZE;
if(p1 == pend) {
p1 = buf;
pend = buf + fread(buf, 1, BUF_SIZE, stdin);
if(pend == p1) {
IOerror = 1;
return -1;
}
}
return *p1++;
}
inline bool blank(char ch) {
return ch == ' ' || ch == '\n' || ch == '\r' || ch == '\t';
}
inline void read(int &x) {
char ch;
while(blank(ch = nc()));
if(IOerror)
return;
for(x = ch - '0'; (ch = nc()) >= '0' && ch <= '9'; x = x * 10 + ch - '0');
}
inline void readll(long long int &x) {
char ch;
while(blank(ch = nc()));
if(IOerror)
return;
for(x = ch - '0'; (ch = nc()) >= '0' && ch <= '9'; x = x * 10 + ch - '0');
}
#undef BUF_SIZE
};
更更“实用”的
struct fast_IO{
/***read***/
char buf[1000000], *s = buf, *t = buf;
inline char gc()
{
#ifdef LOCAL
return getchar();
#endif
return s == t && (t = (s = buf) + fread(buf, 1, 1000000, stdin), s == t) ? EOF : *s ++ ;
}
// read a character
int chtype = 0;
inline void chnormal() {chtype = 0;}
inline void chall() {chtype = 1;}
inline void chdigit() {chtype = 2;}
inline void chletter() {chtype = 3;}
inline char chread()
{
char ch = gc();
while(ch != EOF && ch <= 32) ch = gc();
return ch;
}
inline char digitread()
{
char ch = gc();
while(ch != EOF && (ch < '0' || ch > '9')) ch = gc();
return ch;
}
inline char letterread()
{
char ch = gc();
while(ch != EOF && !('A' <= ch && ch <= 'Z' || 'a' <= ch && ch <= 'z')) ch = gc();
return ch;
}
// read a string
int strtype = 0;
inline void strnormal() {strtype = 0;}
inline void strline() {strtype = 1;}
inline void strread(char *s)
{
char ch = gc();
while(ch <= 32) ch = gc();
while(ch > 32) *s ++ = ch, ch = gc();
*s = 0;
}
inline void lineread(char *s)
{
char ch = gc();
while(ch < 32) ch = gc();
while(ch >= 32) *s ++ = ch, ch = gc();
*s = 0;
}
// read an integer
int inttype = 0;
inline void intnormal() {inttype = 0;}
inline void intunsigned() {inttype = 1;}
inline unsigned uread()
{
char ch = gc();
unsigned x = 0;
while(ch < '0' || ch > '9') ch = gc();
while('0' <= ch && ch <= '9') x = (x << 1) + (x << 3) + (ch ^ 48), ch = gc();
return x;
}
inline int read()
{
char ch = gc();
int x = 0, f = 0;
while(ch < '0' || ch > '9')
{
if(ch == '-') f = 1;
ch = gc();
}
if(f) while('0' <= ch && ch <= '9') x = x * 10 - (ch ^ 48), ch = gc();
else while('0' <= ch && ch <= '9') x = x * 10 + (ch ^ 48), ch = gc();
return x;
}
// read a long long integer
int lltype = 0;
inline void llnormal() {lltype = 0;}
inline void llunsigned() {lltype = 1;}
inline unsigned long long ullread()
{
char ch = gc();
unsigned long long x = 0;
while(ch < '0' || ch > '9') ch = gc();
while('0' <= ch && ch <= '9') x = (x << 1) + (x << 3) + (ch ^ 48), ch = gc();
return x;
}
inline long long llread()
{
char ch = gc();
long long x = 0, f = 0;
while(ch < '0' || ch > '9')
{
if(ch == '-') f = 1;
ch = gc();
}
if(f) while('0' <= ch && ch <= '9') x = x * 10 - (ch ^ 48), ch = gc();
else while('0' <= ch && ch <= '9') x = x * 10 + (ch ^ 48), ch = gc();
return x;
}
// read a real number
inline double dread()
{
char ch = gc();
double x = 0, f = 1;
while(ch < '0' || ch > '9')
{
if(ch == '-') f = -1;
ch = gc();
}
while('0' <= ch && ch <= '9') x = x * 10 + (ch ^ 48), ch = gc();
if(ch == '.')
{
ch = gc();
double p = 0.1;
while('0' <= ch && ch <= '9') x += p * (ch ^ 48), ch = gc(), p *= 0.1;
}
return x * f;
}
inline fast_IO & operator >> (char &x)
{
switch(chtype)
{
case 0 : x = chread(); break ;
case 1 : x = gc(); break ;
case 2 : x = digitread(); break ;
case 4 : x = letterread(); break ;
default : break ;
}
return *this;
}
inline fast_IO & operator >> (char *x)
{
strtype ? lineread(x) : strread(x);
return *this;
}
inline fast_IO & operator >> (string &x)
{
static char buf[1000005];
strtype ? lineread(buf) : strread(buf);
return x = buf, *this;
}
inline fast_IO & operator >> (int &x)
{
inttype ? x = uread() : x = read();
return *this;
}
inline fast_IO & operator >> (unsigned &x)
{
return x = uread(), *this;
}
inline fast_IO & operator >> (long long &x)
{
lltype ? x = ullread() : x = llread();
return *this;
}
inline fast_IO & operator >> (unsigned long long &x)
{
return x = ullread(), *this;
}
inline fast_IO & operator >> (__int128 &x)
{
lltype ? x = ullread() : x = llread();
return *this;
}
inline fast_IO & operator >> (unsigned __int128 &x)
{
return x = ullread(), *this;
}
inline fast_IO & operator >> (float &x)
{
return x = dread(), *this;
}
inline fast_IO & operator >> (double &x)
{
return x = dread(), *this;
}
inline fast_IO & operator >> (long double &x)
{
return x = dread(), *this;
}
inline fast_IO & operator >> (__float128 &x)
{
return x = dread(), *this;
}
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/***write***/
char obuf[1000000], *p = obuf;
const char endl = '\n';
inline void pc(char x)
{
p - obuf < 1000000 ? (*p ++ = x) : (fwrite(obuf, p - obuf, 1, stdout), p = obuf, *p ++ = x);
}
inline ~fast_IO() {fwrite(obuf, p - obuf, 1, stdout);}
inline fast_IO & operator << (int x)
{
if(!x) return pc(48), *this;
int len = 0;
static char c[40];
if(x < 0) pc('-'), x = -x;
while(x) c[ ++ len] = (x % 10) ^ 48, x /= 10;
while(len) pc(c[len -- ]);
return *this;
}
inline fast_IO & operator << (unsigned x)
{
if(!x) return pc(48), *this;
int len = 0;
static char c[40];
if(x < 0) pc('-'), x = -x;
while(x) c[ ++ len] = (x % 10) ^ 48, x /= 10;
while(len) pc(c[len -- ]);
return *this;
}
inline fast_IO & operator << (long long x)
{
if(!x) return pc(48), *this;
int len = 0;
static char c[40];
if(x < 0) pc('-'), x = -x;
while(x) c[ ++ len] = (x % 10) ^ 48, x /= 10;
while(len) pc(c[len -- ]);
return *this;
}
inline fast_IO & operator << (unsigned long long x)
{
if(!x) return pc(48), *this;
int len = 0;
static char c[40];
if(x < 0) pc('-'), x = -x;
while(x) c[ ++ len] = (x % 10) ^ 48, x /= 10;
while(len) pc(c[len -- ]);
return *this;
}
inline fast_IO & operator << (__int128 x)
{
if(!x) return pc(48), *this;
int len = 0;
static char c[40];
if(x < 0) pc('-'), x = -x;
while(x) c[ ++ len] = (x % 10) ^ 48, x /= 10;
while(len) pc(c[len -- ]);
return *this;
}
inline fast_IO & operator << (unsigned __int128 x)
{
if(!x) return pc(48), *this;
int len = 0;
static char c[40];
if(x < 0) pc('-'), x = -x;
while(x) c[ ++ len] = (x % 10) ^ 48, x /= 10;
while(len) pc(c[len -- ]);
return *this;
}
inline fast_IO & operator << (char x)
{
return pc(x), *this;
}
inline fast_IO & operator << (char *x)
{
while(*x) pc(*x ++ );
return *this;
}
inline fast_IO & operator << (string x)
{
for(char i : x) pc(i);
return *this;
}
}IO;
1.5 __int128
struct
使用 cin 和 cout 输入、输出即可
namespace fastio {
struct reader {
template<typename T>reader&operator>>(T&x) {
char c = getchar();
short f = 1;
while (c < '0' || c > '9') {
if (c == '-')f *= -1;
c = getchar();
}
x = 0;
while (c >= '0' && c <= '9') {
x = (x << 1) + (x << 3) + (c ^ 48);
c = getchar();
}
x *= f;
return *this;
}
} cin;
struct writer {
template<typename T>writer&operator<<(T x) {
if (x == 0)return putchar('0'), *this;
if (x < 0)putchar('-'), x = -x;
static int sta[45];
int top = 0;
while (x)sta[++top] = x % 10, x /= 10;
while (top)putchar(sta[top] + '0'), --top;
return*this;
}
} cout;
};
#define cin fastio::cin
#define cout fastio::cout
read && write
#define int __int128
inline void read(int &n) {
int x = 0, f = 1;
char ch = getchar();
while (ch < '0' || ch > '9') {
if (ch == '-') f = -1;
ch = getchar();
}
while (ch >= '0' && ch <= '9') {
x = (x << 1) + (x << 3) + (ch ^ 48);
ch = getchar();
}
n = x * f;
}
inline void write(int n) {
if (n < 0) {
putchar('-');
n *= -1;
}
if (n > 9) write(n / 10);
putchar(n % 10 + '0');
}
#undef int
2.double (float)
容易出现精度问题，建议最好还是用 scanf 和 printf 。
inline double read() {
double x = 0;
int flag = 0;
char ch = 0;
while (!isdigit(ch)) {
flag |= (ch == '-');
ch = getchar();
}
while (isdigit(ch)) {
x = x * 10 + (ch - '0');
ch = getchar();
}
if (ch != '.') return flag ? -x : x;
int f = 1;
ch = getchar();
while (isdigit(ch)) {
x = x + (ch - '0') * pow(10, -f);
f++;
ch = getchar();
}
return flag ? -x : x;
}
inline void write(int x) {
char num[30];
int cnt = 0;
if (x == 0) {
putchar('0');
return;
}
if (x < 0) {
putchar('-');
x = -x;
}
while (x > 0) {
num[cnt++] = x % 10 + '0';
x /= 10;
}
while (cnt > 0) {
putchar(num[--cnt]);
}
}
inline void write(double x) {
write(int(x));
if (x < 0) x = -x;
x -= int(x);
if (x != 0) putchar('.');
while (x) {
x *= 10;
putchar(int(x) + '0');
x -= int(x);
}
}
3.char、char*、char[]、string
NO.1
使用和 cin 和 cout 相同的格式输入、输出，将 c 改为 q 即可
// #define OPENIOBUF
namespace FastIO
{
class FastIOBase
{
protected:
#ifdef OPENIOBUF
static const int BUFSIZE=1<<16;
char buf[BUFSIZE+1];
int buf_p=0;
#endif
FILE *target;
FastIOBase(FILE *f): target(f){}
~FastIOBase()=default;
public:
#ifdef OPENIOBUF
virtual void flush()=0;
#endif
};
class FastOutput final: public FastIOBase
{
private:
void __putc(char x)
{
#ifdef OPENIOBUF
if(buf[buf_p++]=x,buf_p==BUFSIZE) flush();
#else
putc(x,target);
#endif
}
template<typename T>
void __write(T x)
{
char stk[numeric_limits<T>::digits10+1],*top=stk;
if(x<0) return __putc('-'),__write(-x);
do *(top++)=x%10,x/=10; while(x);
for(;top!=stk;__putc(*(--top)+'0'));
}
public:
FastOutput(FILE *f=stdout): FastIOBase(f) {}
#ifdef OPENIOBUF
~FastOutput() { flush(); }
void flush() { fwrite(buf,1,buf_p,target),buf_p=0; }
#endif
FastOutput &operator <<(char x)
{ return __putc(x),*this; }
FastOutput &operator <<(const char *s)
{ for(;*s;__putc(*(s++)));return *this; }
FastOutput &operator <<(const std::string &s)
{ return (*this)<<s.c_str(); }
template<typename T>
std::enable_if_t<std::is_integral<T>::value,FastOutput&> operator <<(const T &x)
{ return __write(x),*this; }
template<typename ...T>
void writesp(const T &...x)
{ std::initializer_list<int>{(this->operator<<(x),__putc(' '),0)...}; }
template<typename ...T>
void writeln(const T &...x)
{ std::initializer_list<int>{(this->operator<<(x),__putc('\n'),0)...}; }
template<typename Iter>
void writesp(Iter begin,Iter end)
{ while(begin!=end) (*this)<<*(begin++)<<' '; }
template<typename Iter>
void writeln(Iter begin,Iter end)
{ while(begin!=end) (*this)<<*(begin++)<<'\n'; }
}qout;
class FastInput final: public FastIOBase
{
private:
bool __eof;
public:
FastInput(FILE *f=stdin): FastIOBase(f),__eof(false)
#ifdef OPENIOBUF
{ buf_p=BUFSIZE; }
void flush() { buf[fread(buf,1,BUFSIZE,target)]=EOF,buf_p=0; }
bool eof()const { return buf[buf_p]==EOF; }
#else
{}
bool eof()const { return feof(target); }
#endif
char get()
{
if(__eof) return EOF;
#ifdef OPENIOBUF
if(buf_p==BUFSIZE) flush();
char ch=buf[buf_p++];
#else
char ch=getc(target);
#endif
return ~ch?ch:(__eof=true,EOF);
}
void unget(char c)
{
__eof=false;
#ifdef OPENIOBUF
buf[--buf_p]=c;
#else
ungetc(c,target);
#endif
}
explicit operator bool()const { return !__eof; }
FastInput &operator >>(char &x)
{ while(isspace(x=get()));return *this; }
template<typename T>
std::enable_if_t<std::is_integral<T>::value,FastInput&> operator >>(T &x)
{
char ch,sym=0;x=0;
while(isspace(ch=get()));
if(__eof) return *this;
if(ch=='-') sym=1,ch=get();
for(;isdigit(ch);x=(x<<1)+(x<<3)+(ch^48),ch=get());
return unget(ch),sym?x=-x:x,*this;
}
FastInput &operator >>(char *s)
{
while(isspace(*s=get()));
if(__eof) return *this;
for(;!isspace(*s) && !__eof;*(++s)=get());
return unget(*s),*s='\0',*this;
}
FastInput &operator >>(std::string &s)
{
char str_buf[(1<<8)+1]={0},*p=str_buf;
char *const buf_end=str_buf+(1<<8);
while(isspace(*p=get()));
if(__eof) return *this;
for(s.clear(),p++;;p=str_buf)
{
for(;p!=buf_end && !isspace(*p=get()) && !__eof;p++);
if(p!=buf_end) break;
s.append(str_buf);
}
unget(*p),*p='\0',s.append(str_buf);
return *this;
}
template<typename ...T>
void read(T &...x)
{ std::initializer_list<int>{(this->operator>>(x),0)...}; }
template<typename Iter>
void read(Iter begin,Iter end)
{ while(begin!=end) (*this)>>*(begin++); }
}qin;
} // namespace FastIO
using FastIO::qin,FastIO::qout;
NO.2
同 cin 和 cout 的格式，将 c 改为 f
namespace fastio
{
const int bufl=1<<20;
const double base1[16]={1,1e-1,1e-2,1e-3,1e-4,1e-5,1e-6,1e-7,1e-8,1e-9,1e-10,1e-11,1e-12,1e-13,1e-14,1e-15};
const double base2[16]={1,1e1,1e2,1e3,1e4,1e5,1e6,1e7,1e8,1e9,1e10,1e11,1e12,1e13,1e14,1e15};
struct IN{
FILE *IT;char ibuf[bufl],*is=ibuf,*it=ibuf;
IN(){IT=stdin;}IN(char *a){IT=fopen(a,"r");}
inline char getChar(){if(is==it){it=(is=ibuf)+fread(ibuf,1,bufl,IT);if(is==it)return EOF;}return *is++;}
template<typename Temp>inline void getInt(Temp &a){a=0;int b=0,c=getChar();while(c<48||c>57)b^=(c==45),c=getChar();while(c>=48&&c<=57)a=(a<<1)+(a<<3)+c-48,c=getChar();if(b)a=-a;}
template<typename Temp>inline void getDouble(Temp &a){a=0;int b=0,c=getChar(),d=0;__int128 e=0,f=0;while(c<48||c>57)b^=(c==45),c=getChar();while(c>=48&&c<=57)e=(e<<1)+(e<<3)+c-48,c=getChar();if(c==46){c=getChar();while(c>=48&&c<=57)d++,f=(f<<1)+(f<<3)+c-48,c=getChar();}a=e+base1[d]*f;if(b)a=-a;}
IN& operator>>(char &a){a=getChar();return *this;}
IN& operator>>(char *a){do{*a=getChar();}while(*a<=32);while(*a>32)*++a=getChar();*a=0;return *this;}
IN& operator>>(string &a){char b=getChar();while(b<=32)b=getChar();while(b>32)a+=b,b=getChar();return *this;}
IN& operator>>(int &a){getInt(a);return *this;}
IN& operator>>(long long &a){getInt(a);return *this;}
IN& operator>>(__int128 &a){getInt(a);return *this;}
IN& operator>>(float &a){getDouble(a);return *this;}
IN& operator>>(double &a){getDouble(a);return *this;}
IN& operator>>(long double &a){getDouble(a);return *this;}
};
struct OUT{
FILE *IT;char obuf[bufl],*os=obuf,*ot=obuf+bufl;int Eps;long double Acc;
OUT(){IT=stdout,Eps=6,Acc=1e-6;}OUT(char *a){IT=fopen(a,"w"),Eps=6,Acc=1e-6;}
inline void ChangEps(int x=6){Eps=x;}
inline void flush(){fwrite(obuf,1,os-obuf,IT);os=obuf;}
inline void putChar(int a){*os++=a;if(os==ot)flush();}
template<typename Temp>inline void putInt(Temp a){if(a<0){putChar(45);a=-a;}if(a<10){putChar(a+48);return;}putInt(a/10);putChar(a%10+48);}
template<typename Temp>inline void putLeading(Temp a,int b){if(!b)return;putLeading(a/10,b-1);putChar(a%10+48);}
template<typename Temp>inline void putDouble(Temp a){if(a<0){putChar(45);a=-a;}__int128 b=a;putInt(b);a-=b;a*=base2[Eps];b=a+Acc;putChar(46);putLeading(b,Eps);}
OUT& operator<<(char a){putChar(a);return *this;}
OUT& operator<<(char *a){while(*a>32)putChar(*a++);return *this;}
OUT& operator<<(string a){for(auto c:a)putChar(c);return *this;}
OUT& operator<<(int a){putInt(a);return *this;}
OUT& operator<<(long long a){putInt(a);return *this;}
OUT& operator<<(__int128 a){putInt(a);return *this;}
OUT& operator<<(float a){putDouble(a);return *this;}
OUT& operator<<(double a){putDouble(a);return *this;}
OUT& operator<<(long double a){putDouble(a);return *this;}
~OUT(){flush();}
};
}
using fastio::IN;
using fastio::OUT;
IN fin;
OUT fout;