Submission #99776

#	Time	Username	Problem	Language	Result	Execution time	Memory
99776		PeppaPig	Crayfish scrivener (IOI12_scrivener)	C++14	100 / 100	960 ms	129308 KiB

scrivener

#include <bits/stdc++.h>

using namespace std;

const int N = 1e6+5;

struct node {
    char d;
    int sz;
    node *par[20];
    node() { }
    node(char d) : d(d) { for(int i = 0; i <= 19; i++) par[i] = NULL; }
};

int ptr;
node* S[N];

void Init() {
    ptr = 0;
    S[0] = NULL; 
}

void TypeLetter(char L) {
    ++ptr;
    S[ptr] = new node(L);
    S[ptr]->sz = S[ptr-1] ? S[ptr-1]->sz + 1 : 1;
    S[ptr]->par[0] = S[ptr-1];
    for(int i = 1; i <= 19; i++) if(S[ptr]->par[i-1])
        S[ptr]->par[i] = S[ptr]->par[i-1]->par[i-1];
}

void UndoCommands(int U) {
    S[++ptr] = S[ptr - U];
}

char GetLetter(int P) {
    int d = S[ptr]->sz - P - 1;
    node* now = S[ptr];
    for(int i = 19; ~i; i--) if(d >> i & 1) now = now->par[i];
    return now->d;
}

Compilation message (stderr)

scrivener.cpp: In function 'void UndoCommands(int)':
scrivener.cpp:33:7: warning: operation on 'ptr' may be undefined [-Wsequence-point]
     S[++ptr] = S[ptr - U];
       ^~~~~

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 22 / 22
• Subtask 4: 26 / 26
• Subtask 5: 40 / 40