Submission #257225

#	Time	Username	Problem	Language	Result	Execution time	Memory
257225		2qbingxuan	Cave (IOI13_cave)	C++14	100 / 100	972 ms	888 KiB

cave

#include "cave.h"
inline int __lg(int n) { return 31 - __builtin_clz(n); }
int on[5025];
int n;
int D[5025], S[5025];
int checkPrefix(int x, int d) {
    for(int i = 0; i < n; i++) {
        if(D[i] == -1)
            on[i] = (i < x) ^ d;
    }
    return tryCombination(on);
}
void exploreCave(int _n) {
  	n = _n;
    for(int i = 0; i < n; i++) D[i] = -1;
    for(int now = 0; now < n; now++) {
        if(checkPrefix(n, 0) == now) { // all on -> now should be off
            int x = 0;
            for(int s = 1<<__lg(n); s; s>>=1) if(x+s < n && checkPrefix(x+s, 1) == now) x += s;
            D[x] = now;
            S[x] = on[x] = 0;
        } else {
            int x = 0;
            for(int s = 1<<__lg(n); s; s>>=1) if(x+s < n && checkPrefix(x+s, 0) == now) x += s;
            D[x] = now;
            S[x] = on[x] = 1;
        }
    }
    answer(S, D);
}

• Subtask 1: 12 / 12
• Subtask 2: 13 / 13
• Subtask 3: 21 / 21
• Subtask 4: 30 / 30
• Subtask 5: 24 / 24