Submission #1006602

#	Time	Username	Problem	Language	Result	Execution time	Memory
1006602		farrellw	Wall (IOI14_wall)	C++14	100 / 100	423 ms	48916 KiB

wall

#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define INF 1000000
typedef pair<int, int> ii;
typedef vector<int> vi;
typedef vector<ii> vii;

#include "wall.h"

ii combine(ii upd_new, ii upd_old) {    // apply upd_new to upd_old
    ii res = {max(upd_new.fi, upd_old.fi), min(upd_new.se, upd_old.se)};
    if (res.fi > res.se) { // The ranges are disjoint, so suffices to check either
        res = (upd_old.se < upd_new.se) ? make_pair(upd_new.fi, upd_new.fi) : make_pair(upd_new.se, upd_new.se);
    }
    return res;
}

struct Segtree {    // Segtree of updates
    int sz;
    vector<ii> upd;    // store (a, b)
    Segtree(int N) {
        sz = 1;
        while (sz < N)
            sz *= 2;
        upd = vii(2 * sz, {0, INF});
    }
    void push(int id, int left, int right) { // O(1), for regular updates
        if (right - left == 1)
            return;
        upd[2 * id + 1] = combine(upd[id], upd[2 * id + 1]);
        upd[2 * id + 2] = combine(upd[id], upd[2 * id + 2]);
        upd[id] = {0, INF};
    }

    void push_recursive(int id, int left, int right) { // O(N), only for answer extraction at the end
        if(right - left == 1)
            return;
        push(id, left, right);
        int mid = (left + right) / 2;
        push_recursive(2 * id + 1, left, mid);
        push_recursive(2 * id + 2, mid, right);
    }

    void range_upd(int qleft, int qright, ii val, int id, int left, int right) {
        if (qleft <= left && right <= qright) {
            upd[id] = combine(val, upd[id]);
            return;
        }
        if (qright <= left || right <= qleft)
            return;
        push(id, left, right);
        int mid = (left + right) / 2;
        range_upd(qleft, qright, val, 2 * id + 1, left, mid);
        range_upd(qleft, qright, val, 2 * id + 2, mid, right);
    }
    void range_upd(int qleft, int qright, ii val) {
        range_upd(qleft, qright, val, 0, 0, sz);
    }
};

void buildWall(int n, int k, int op[], int left[], int right[], int height[], int finalHeight[]) {
    Segtree tree(n);
    for(int z = 0; z < k; z++) {
        ii upd_val = (op[z] == 1) ? make_pair(height[z], INF) : make_pair(0, height[z]);
        tree.range_upd(left[z], right[z]+1, upd_val);
    }
    tree.push_recursive(0, 0, tree.sz);
    for(int z = 0; z < n; z++) {
        finalHeight[z] = tree.upd[z+tree.sz-1].fi;
    }
    return;
}

• Subtask 1: 8 / 8
• Subtask 2: 24 / 24
• Subtask 3: 29 / 29
• Subtask 4: 39 / 39