Submission #444334

#	Time	Username	Problem	Language	Result	Execution time	Memory
444334		parsabahrami	The short shank; Redemption (BOI21_prison)	C++17	70 / 100	520 ms	6216 KiB

prison

/* I do it for the glory */
#include <bits/stdc++.h>
 
using namespace std;

typedef long long int ll;
typedef pair<double, int> pii;
 
#define SZ(x)                       (int) x.size()
#define F                           first
#define S                           second
#define lc                          id << 1
#define rc                          lc | 1

const int N = 7.5e4 + 10, MOD = 1e9 + 7; const double eps = 1e-14;
int R[N], t[N], n, T, D; pii dp[N], seg[N << 2];

void bld(int id = 1, int l = 1, int r = n + 1) {
    seg[id] = {MOD, 0};
    if (r - l < 2) return;
    int md = (l + r) >> 1;
    bld(lc, l, md), bld(rc, md, r);
}

void upd(int p, double x, int y, int id = 1, int l = 1, int r = n + 1) {
    if (r - l < 2) { seg[id] = min(seg[id], {x, y}); return; }
    int md = (l + r) >> 1;
    p < md ? upd(p, x, y, lc, l, md) : upd(p, x, y, rc, md, r);
    seg[id] = min(seg[lc], seg[rc]);
}

pii get(int ql, int qr, int id = 1, int l = 1, int r = n + 1) {
    if (qr <= l || r <= ql) return {MOD, 0};
    if (ql <= l && r <= qr) { return seg[id]; }
    int md = (l + r) >> 1;
    return min(get(ql, qr, lc, l, md), get(ql, qr, rc, md, r));
}

pii get(double l) {
    bld(); fill(dp, dp + n + 2, pii(0.0, 0));
    if (t[n] <= T) dp[n] = {1.0, 0};
    else dp[n] = {0.0, 0};
    upd(n, dp[n].F + n, dp[n].S);
    for (int i = n - 1; i; i--) {
        if (R[i] < i) 
            if (l <= 0) dp[i] = {dp[i + 1].F + l, dp[i + 1].S + 1};
            else dp[i] = dp[i + 1];
        else {
            pii x = get(i + 1, R[i] + 2);
            dp[i] = {x.F + l - i, x.S + 1};
            dp[i] = min(dp[i], {dp[R[i] + 1].F + R[i] - i + 1, dp[R[i] + 1].S});
        }
        upd(i, dp[i].F + i, dp[i].S);
    }
    return dp[1];
}

int main() {
    scanf("%d%d%d", &n, &D, &T);
    assert(n <= N);
    for (int i = 1; i <= n; i++) 
        scanf("%d", &t[i]);
    for (int i = n; i; i--) {
        for (R[i] = i + 1; R[i] <= n && t[R[i]] - R[i] > t[i] - i; R[i] = R[R[i]]);
    }
    for (int i = n; i; i--) {
        if (R[i] <= min(n, i + T - t[i])) 
            R[i] = R[R[i]];
        else R[i] = min(n, i + T - t[i]);
        if (R[i] < i) R[i] = -1;
    }
    double l = -N, r = N;
    for (; r - l > 1; ) {
        double md = (l + r) / 2.0;
        if (get(md).S >= D) l = md;
        else r = md;
    }
    if (get(l).S == D) {
        int ret = get(l).F - l * D;
        printf("%d\n", ret);
    } else {
        pii A = get(l); int x = A.F - l * A.S;
        pii B = get(r); int y = B.F - r * B.S;
        printf("%d\n", y + (D - B.S) * (x - y) / (A.S - B.S));
    }
    return 0;
}

Compilation message (stderr)

prison.cpp: In function 'int main()':
prison.cpp:59:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   59 |     scanf("%d%d%d", &n, &D, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~
prison.cpp:62:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   62 |         scanf("%d", &t[i]);
      |         ~~~~~^~~~~~~~~~~~~

• Subtask 1: 15 / 15
• Subtask 2: 0 / 10
• Subtask 3: 20 / 20
• Subtask 4: 10 / 10
• Subtask 5: 25 / 25
• Subtask 6: 0 / 20