思路：
维护头两个0的位置，然后模拟。这里记录一种快读模板。
实现：
1 #include<bits/stdc++.h> 2 using namespace std; 3 namespace fastIO{ 4 #define BUF_SIZE 1000000 5 #define OUT_SIZE 1000000 6 #define ll long long 7 //fread->read 8 bool IOerror=0; 9 inline char nc(){ 10 static char buf[BUF_SIZE],*p1=buf+BUF_SIZE,*pend=buf+BUF_SIZE; 11 if (p1==pend){ 12 p1=buf; pend=buf+fread(buf,1,BUF_SIZE,stdin); 13 if (pend==p1){IOerror=1;return -1;} 14 //{printf("IO error!\n");system("pause");for (;;);exit(0);} 15 } 16 return *p1++; 17 } 18 inline bool blank(char ch){return ch==' '||ch=='\n'||ch=='\r'||ch=='\t';} 19 inline void read(int &x){ 20 bool sign=0; char ch=nc(); x=0; 21 for (;blank(ch);ch=nc()); 22 if (IOerror)return; 23 if (ch=='-')sign=1,ch=nc(); 24 for (;ch>='0'&&ch<='9';ch=nc())x=x*10+ch-'0'; 25 if (sign)x=-x; 26 } 27 inline void read(ll &x){ 28 bool sign=0; char ch=nc(); x=0; 29 for (;blank(ch);ch=nc()); 30 if (IOerror)return; 31 if (ch=='-')sign=1,ch=nc(); 32 for (;ch>='0'&&ch<='9';ch=nc())x=x*10+ch-'0'; 33 if (sign)x=-x; 34 } 35 inline void read(double &x){ 36 bool sign=0; char ch=nc(); x=0; 37 for (;blank(ch);ch=nc()); 38 if (IOerror)return; 39 if (ch=='-')sign=1,ch=nc(); 40 for (;ch>='0'&&ch<='9';ch=nc())x=x*10+ch-'0'; 41 if (ch=='.'){ 42 double tmp=1; ch=nc(); 43 for (;ch>='0'&&ch<='9';ch=nc())tmp/=10.0,x+=tmp*(ch-'0'); 44 } 45 if (sign)x=-x; 46 } 47 inline void read(char *s){ 48 char ch=nc(); 49 for (;blank(ch);ch=nc()); 50 if (IOerror)return; 51 for (;!blank(ch)&&!IOerror;ch=nc())*s++=ch; 52 *s=0; 53 } 54 inline void read(char &c){ 55 for (c=nc();blank(c);c=nc()); 56 if (IOerror){c=-1;return;} 57 } 58 //getchar->read 59 inline void read1(int &x){ 60 char ch;int bo=0;x=0; 61 for (ch=getchar();ch<'0'||ch>'9';ch=getchar())if (ch=='-')bo=1; 62 for (;ch>='0'&&ch<='9';x=x*10+ch-'0',ch=getchar()); 63 if (bo)x=-x; 64 } 65 inline void read1(ll &x){ 66 char ch;int bo=0;x=0; 67 for (ch=getchar();ch<'0'||ch>'9';ch=getchar())if (ch=='-')bo=1; 68 for (;ch>='0'&&ch<='9';x=x*10+ch-'0',ch=getchar()); 69 if (bo)x=-x; 70 } 71 inline void read1(double &x){ 72 char ch;int bo=0;x=0; 73 for (ch=getchar();ch<'0'||ch>'9';ch=getchar())if (ch=='-')bo=1; 74 for (;ch>='0'&&ch<='9';x=x*10+ch-'0',ch=getchar()); 75 if (ch=='.'){ 76 double tmp=1; 77 for (ch=getchar();ch>='0'&&ch<='9';tmp/=10.0,x+=tmp*(ch-'0'),ch=getchar()); 78 } 79 if (bo)x=-x; 80 } 81 inline void read1(char *s){ 82 char ch=getchar(); 83 for (;blank(ch);ch=getchar()); 84 for (;!blank(ch);ch=getchar())*s++=ch; 85 *s=0; 86 } 87 inline void read1(char &c){for (c=getchar();blank(c);c=getchar());} 88 //scanf->read 89 inline void read2(int &x){scanf("%d",&x);} 90 inline void read2(ll &x){ 91 #ifdef _WIN32 92 scanf("%I64d",&x); 93 #else 94 #ifdef __linux 95 scanf("%lld",&x); 96 #else 97 puts("error:can't recognize the system!"); 98 #endif 99 #endif 100 } 101 inline void read2(double &x){scanf("%lf",&x);} 102 inline void read2(char *s){scanf("%s",s);} 103 inline void read2(char &c){scanf(" %c",&c);} 104 inline void readln2(char *s){gets(s);} 105 //fwrite->write 106 struct Ostream_fwrite{ 107 char *buf,*p1,*pend; 108 Ostream_fwrite(){buf=new char[BUF_SIZE];p1=buf;pend=buf+BUF_SIZE;} 109 void out(char ch){ 110 if (p1==pend){ 111 fwrite(buf,1,BUF_SIZE,stdout);p1=buf; 112 } 113 *p1++=ch; 114 } 115 void print(int x){ 116 static char s[15],*s1;s1=s; 117 if (!x)*s1++='0';if (x<0)out('-'),x=-x; 118 while(x)*s1++=x%10+'0',x/=10; 119 while(s1--!=s)out(*s1); 120 } 121 void println(int x){ 122 static char s[15],*s1;s1=s; 123 if (!x)*s1++='0';if (x<0)out('-'),x=-x; 124 while(x)*s1++=x%10+'0',x/=10; 125 while(s1--!=s)out(*s1); out('\n'); 126 } 127 void print(ll x){ 128 static char s[25],*s1;s1=s; 129 if (!x)*s1++='0';if (x<0)out('-'),x=-x; 130 while(x)*s1++=x%10+'0',x/=10; 131 while(s1--!=s)out(*s1); 132 } 133 void println(ll x){ 134 static char s[25],*s1;s1=s; 135 if (!x)*s1++='0';if (x<0)out('-'),x=-x; 136 while(x)*s1++=x%10+'0',x/=10; 137 while(s1--!=s)out(*s1); out('\n'); 138 } 139 void print(char *s){while (*s)out(*s++);} 140 void println(char *s){while (*s)out(*s++);out('\n');} 141 void flush(){if (p1!=buf){fwrite(buf,1,p1-buf,stdout);p1=buf;}} 142 ~Ostream_fwrite(){flush();} 143 }Ostream; 144 inline void print(int x){Ostream.print(x);} 145 inline void println(int x){Ostream.println(x);} 146 inline void print(char x){Ostream.out(x);} 147 inline void println(char x){Ostream.out(x);Ostream.out('\n');} 148 inline void print(ll x){Ostream.print(x);} 149 inline void println(ll x){Ostream.println(x);} 150 inline void print(char *s){Ostream.print(s);} 151 inline void println(char *s){Ostream.println(s);} 152 inline void println(){Ostream.out('\n');} 153 inline void flush(){Ostream.flush();} 154 //puts->write 155 char Out[OUT_SIZE],*o=Out; 156 inline void print1(int x){ 157 static char buf[15]; 158 char *p1=buf;if (!x)*p1++='0';if (x<0)*o++='-',x=-x; 159 while(x)*p1++=x%10+'0',x/=10; 160 while(p1--!=buf)*o++=*p1; 161 } 162 inline void println1(int x){print1(x);*o++='\n';} 163 inline void print1(ll x){ 164 static char buf[25]; 165 char *p1=buf;if (!x)*p1++='0';if (x<0)*o++='-',x=-x; 166 while(x)*p1++=x%10+'0',x/=10; 167 while(p1--!=buf)*o++=*p1; 168 } 169 inline void println1(ll x){print1(x);*o++='\n';} 170 inline void print1(char c){*o++=c;} 171 inline void println1(char c){*o++=c;*o++='\n';} 172 inline void print1(char *s){while (*s)*o++=*s++;} 173 inline void println1(char *s){print1(s);*o++='\n';} 174 inline void println1(){*o++='\n';} 175 inline void flush1(){if (o!=Out){if (*(o-1)=='\n')*--o=0;puts(Out);}} 176 struct puts_write{ 177 ~puts_write(){flush1();} 178 }_puts; 179 inline void print2(int x){printf("%d",x);} 180 inline void println2(int x){printf("%d\n",x);} 181 inline void print2(char x){printf("%c",x);} 182 inline void println2(char x){printf("%c\n",x);} 183 inline void print2(ll x){ 184 #ifdef _WIN32 185 printf("%I64d",x); 186 #else 187 #ifdef __linux 188 printf("%lld",x); 189 #else 190 puts("error:can't recognize the system!"); 191 #endif 192 #endif 193 } 194 inline void println2(ll x){print2(x);printf("\n");} 195 inline void println2(){printf("\n");} 196 #undef ll 197 #undef OUT_SIZE 198 #undef BUF_SIZE 199 }; 200 int main(){ 201 //freopen("in.txt","r",stdin); 202 int n; 203 fastIO::read(n); 204 vector<int>v(n+1,0); 205 int l=1,r=2; 206 for(int i=0;i<n;i++){ 207 int t,x; 208 fastIO::read(t); 209 fastIO::read(x); 210 if(t==1){ 211 if(x==l){ 212 l=r; 213 int i=r+1; 214 while(i<=n and v[i]==1)i++; 215 r=i; 216 } 217 else if(x==r){ 218 int i=r+1; 219 while(i<=n and v[i]==1)i++; 220 r=i; 221 } 222 v[x]=1; 223 } 224 else{ 225 if(x==l){ 226 fastIO::println(r); 227 } 228 else{ 229 fastIO::println(l); 230 } 231 } 232 } 233 return 0; 234 }