这是一道模拟内存分配操作的题目，几乎包含了线段树的各种基本操作，跟poj3667 hotel差不多的功能，只是多了一个统计区间个数的操作。
由于这题是断断续续打上去的，花的时间也比较长。可能有些代码写的不太好。
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1 #include <stdio.h> 2 #define lson l,m,rt<<1 3 #define rson m+1,r,rt<<1|1 4 #define maxn 50005 5 struct node 6 { 7 int llen,rlen,maxlen,lnum,rnum,num,cnt; 8 }setree[maxn<<2]; 9 struct 10 { 11 int l,r,c; 12 }idnum[maxn]; 13 int top,cnt; 14 int max(int a,int b) 15 { 16 return a>b?a:b; 17 } 18 void build(int l,int r,int rt) 19 { 20 setree[rt].llen=setree[rt].rlen=setree[rt].maxlen=r-l+1; 21 setree[rt].num=setree[rt].lnum=setree[rt].rnum=-1; 22 setree[rt].cnt=0; 23 if(l==r) 24 return ; 25 int m=(l+r)>>1; 26 build(lson); 27 build(rson); 28 } 29 void pushup(int rt,int len) 30 { 31 setree[rt].llen=setree[rt<<1].llen; 32 setree[rt].lnum=setree[rt<<1].lnum; 33 if(setree[rt<<1].llen==len-len/2) 34 setree[rt].llen+=setree[rt<<1|1].llen; 35 36 setree[rt].rlen=setree[rt<<1|1].rlen; 37 setree[rt].rnum=setree[rt<<1|1].rnum; 38 if(setree[rt<<1|1].rlen==len/2) 39 setree[rt].rlen+=setree[rt<<1].rlen; 40 41 setree[rt].maxlen=max(setree[rt<<1].maxlen,setree[rt<<1|1].maxlen); 42 setree[rt].maxlen=max(setree[rt].maxlen,setree[rt<<1].rlen+setree[rt<<1|1].llen); 43 44 setree[rt].cnt=setree[rt<<1].cnt+setree[rt<<1|1].cnt; 45 if(setree[rt<<1].rnum==setree[rt<<1|1].lnum&&setree[rt<<1].rnum>0) 46 setree[rt].cnt--; 47 } 48 void pushdown(int rt,int len) 49 { 50 if(setree[rt].num!=-1){ 51 setree[rt<<1].llen=setree[rt<<1].rlen=setree[rt<<1].maxlen=setree[rt].num?0:len-len/2; 52 setree[rt<<1|1].llen=setree[rt<<1|1].rlen=setree[rt<<1|1].maxlen=setree[rt].num?0:len/2; 53 setree[rt<<1].lnum=setree[rt<<1].rnum=setree[rt<<1].num=setree[rt].num; 54 setree[rt<<1|1].lnum=setree[rt<<1|1].rnum=setree[rt<<1|1].num=setree[rt].num; 55 setree[rt<<1].cnt=setree[rt<<1|1].cnt=setree[rt].num?1:0; 56 setree[rt].num=-1; 57 } 58 } 59 void update(int l,int r,int rt,int L,int R,int op) 60 { 61 if(L<=l&&r<=R){ 62 setree[rt].llen=setree[rt].rlen=setree[rt].maxlen=op?0:r-l+1; 63 setree[rt].num=setree[rt].lnum=setree[rt].rnum=op; 64 setree[rt].cnt=op?1:0; 65 return ; 66 } 67 pushdown(rt,r-l+1); 68 int m=(l+r)>>1; 69 if(L<=m) 70 update(lson,L,R,op); 71 if(R>m) 72 update(rson,L,R,op); 73 pushup(rt,r-l+1); 74 } 75 int query(int l,int r,int rt,int num) 76 { 77 if(l==r) 78 return l; 79 pushdown(rt,r-l+1); 80 int m=(l+r)>>1; 81 if(setree[rt<<1].maxlen>=num) 82 return query(lson,num); 83 else if(setree[rt<<1].rlen+setree[rt<<1|1].llen>=num) 84 return m-setree[rt<<1].rlen+1; 85 else 86 return query(rson,num); 87 } 88 int query1(int l,int r,int rt,int num) 89 { 90 if(l==r) 91 return setree[rt].num; 92 pushdown(rt,r-l+1); 93 int m=(l+r)>>1; 94 if(num<=m) 95 return query1(lson,num); 96 else 97 return query1(rson,num); 98 } 99 int query2(int l,int r,int rt,int num) 100 { 101 if(l==r) 102 return l; 103 pushdown(rt,r-l+1); 104 int m=(l+r)>>1; 105 if(setree[rt<<1].cnt>=num) 106 return query2(lson,num); 107 else{ 108 num-=setree[rt<<1].cnt; 109 if(setree[rt<<1].cnt+setree[rt<<1|1].cnt>setree[rt].cnt) 110 num++; 111 return query2(rson,num); 112 } 113 } 114 int main() 115 { 116 int n,m,i; 117 while(~scanf("%d%d",&n,&m)){ 118 build(1,n,1); 119 top=1; 120 while(m--){ 121 char opp[5]; 122 int a; 123 scanf("%s",opp); 124 if(opp[0]=='N'){ 125 scanf("%d",&a); 126 if(a>setree[1].maxlen){ 127 printf("Reject New\n"); 128 continue; 129 } 130 int start=query(1,n,1,a); 131 printf("New at %d\n",start); 132 update(1,n,1,start,start+a-1,top); 133 idnum[top].l=start; 134 idnum[top].r=start+a-1; 135 idnum[top].c=1; 136 top++; 137 } 138 else if(opp[0]=='R'){ 139 top=1; 140 printf("Reset Now\n"); 141 update(1,n,1,1,n,0); 142 } 143 else if(opp[0]=='F'){ 144 scanf("%d",&a); 145 int ans=query1(1,n,1,a); 146 if(ans==0||ans==-1){ 147 printf("Reject Free\n"); 148 continue; 149 } 150 printf("Free from %d to %d\n",idnum[ans].l,idnum[ans].r); 151 update(1,n,1,idnum[ans].l,idnum[ans].r,0); 152 idnum[ans].c=0; 153 } 154 else{ 155 scanf("%d",&a); 156 if(a>setree[1].cnt){ 157 printf("Reject Get\n"); 158 continue; 159 } 160 int ans=query2(1,n,1,a); 161 printf("Get at %d\n",ans); 162 } 163 } 164 printf("\n"); 165 } 166 return 0; 167 }