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对着书敲的，，学习一波
  1 #include <cstdio>
  2 #include <cstring>
  3 using namespace std;
  4 
  5 const int MAXL = 2 * 1024 * 1024 + 100;  
  6 const int BLOCK_SIZE = 5000;
  7 const int BLOCK_NUM = MAXL / BLOCK_SIZE * 2 + 100;
  8 int indexPool[BLOCK_NUM];
  9 int blockNum;
 10 int nxt[BLOCK_NUM], curSize[BLOCK_NUM];
 11 char data[BLOCK_NUM][BLOCK_SIZE];
 12 
 13 void init(){
 14     for(int i = 1; i < BLOCK_NUM; i++){
 15         indexPool[i] = i;
 16     }
 17     blockNum = 1;
 18     nxt[0] = -1;
 19     curSize[0] = 0;
 20 }
 21 int getNewBlock(){
 22     return indexPool[blockNum++];
 23 }
 24 void deleteBlock(int blockIndex){
 25     indexPool[--blockNum] = blockIndex;
 26 }
 27 int getCurBlock(int &pos){
 28     int blockIndex = 0;
 29     while(blockIndex != -1 && pos > curSize[blockIndex]){
 30         pos -= curSize[blockIndex];
 31         blockIndex = nxt[blockIndex];
 32     }
 33     return blockIndex;
 34 }
 35 void addNewBlock(int curBlock, int newBlock, int num, char str[]){
 36     if(newBlock != -1){
 37         nxt[newBlock] = nxt[curBlock];
 38         curSize[newBlock] = num;
 39         memcpy(data[newBlock], str, num);
 40     }
 41     nxt[curBlock] = newBlock;
 42 }
 43 
 44 void split(int curBlock, int pos){
 45     if(curBlock == -1 || pos == curSize[curBlock]) return ;
 46     int newBlock = getNewBlock();
 47     addNewBlock(curBlock, newBlock, curSize[curBlock] - pos, data[curBlock] + pos);
 48     curSize[curBlock] = pos;
 49 }
 50 
 51 void merge(int curBlock, int nxtBlock){
 52     memcpy(data[curBlock] + curSize[curBlock], data[nxtBlock], curSize[nxtBlock]);
 53     curSize[curBlock] += curSize[nxtBlock];
 54     nxt[curBlock] = nxt[nxtBlock];
 55     deleteBlock(nxtBlock);
 56 }
 57 void maintainList(){
 58     int curBlock = 0;
 59     while(curBlock != -1){
 60         int nxtBlock = nxt[curBlock];
 61         while(nxtBlock != -1 && curSize[curBlock] + curSize[nxtBlock] <= BLOCK_SIZE){
 62             merge(curBlock, nxtBlock);
 63             nxtBlock = nxt[curBlock];
 64         }
 65         curBlock = nxt[curBlock];
 66     }
 67 }
 68 void insert(int pos, int num, char str[]){
 69     int curBlock = getCurBlock(pos);
 70     split(curBlock, pos);
 71     int curNum = 0;
 72     while(curNum + BLOCK_SIZE <= num){
 73         int newBlock = getNewBlock();
 74         addNewBlock(curBlock, newBlock, BLOCK_SIZE, str + curNum);
 75         curBlock = newBlock;
 76         curNum += BLOCK_SIZE;
 77     }
 78     if(num - curNum){
 79         int newBlock = getNewBlock();
 80         addNewBlock(curBlock, newBlock, num - curNum, str + curNum);
 81     }
 82     maintainList();
 83 }
 84 void erase(int pos, int num){
 85     int curBlock = getCurBlock(pos);
 86     split(curBlock, pos);
 87     int nxtBlock = nxt[curBlock];
 88     while(nxtBlock != -1 && num > curSize[nxtBlock]){
 89         num -= curSize[nxtBlock];
 90         nxtBlock = nxt[nxtBlock];
 91     }
 92     split(nxtBlock, num);
 93     nxtBlock = nxt[nxtBlock];
 94     for(int p = nxt[curBlock]; p != nxtBlock; p = nxt[curBlock]){
 95         nxt[curBlock] = nxt[p];
 96         deleteBlock(p);
 97     }
 98     maintainList();
 99 }
100 
101 void getData(int pos, int num, char str[]){
102     int curBlock = getCurBlock(pos);
103     int index = curSize[curBlock] - pos;
104     if(num < index) index = num;
105     memcpy(str, data[curBlock] + pos, index);
106     int tmpBlock = nxt[curBlock];
107     while(tmpBlock != -1 && index + curSize[tmpBlock] <= num){
108         memcpy(str + index, data[tmpBlock], curSize[tmpBlock]);
109         index += curSize[tmpBlock];
110         tmpBlock = nxt[tmpBlock];
111     }
112     if(num - index && tmpBlock != -1){
113         memcpy(str + index, data[tmpBlock], num - index);
114     }
115     str[num] = '';
116 }
117 
118 char str[MAXL], cd[20];
119 int main(){
120     init();
121     int curPos = 0;
122     int opNum, num;
123     char ch;
124     scanf("%d", &opNum);
125     while(opNum--){
126         scanf("%s", cd);
127         if(cd[0] == 'M'){
128             scanf("%d", &curPos);
129         }else if(cd[0] == 'I'){
130             scanf("%d", &num);
131             for(int i = 0; i < num; i++){
132                 scanf("%c", &ch);
133                 str[i] = ch;
134                 if(ch < 32 || ch > 126) --i;
135             }
136             insert(curPos, num, str);
137         }else if(cd[0] == 'D'){
138             scanf("%d", &num);
139             erase(curPos, num);
140         }else if(cd[0] == 'G'){
141             scanf("%d", &num);
142             getData(curPos, num, str);
143             printf("%s
", str);
144         }else if(cd[0] == 'P'){
145             --curPos;
146         }else if(cd[0] == 'N'){
147             ++curPos;
148         }
149     }
150     return 0;
151 }
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