Submission #579610

#	Time	Username	Problem	Language	Result	Execution time	Memory
579610		LOLOLO	Rabbit Carrot (LMIO19_triusis)	C++17	100 / 100	74 ms	5592 KiB

triusis

#include <bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define pii pair<long long, long long>
#define st first
#define nd second
#define file "test"
using namespace std;
const long long oo = 1e18;
const long long N = 2e5 + 5;
 
int n, m, h[2*N], dp[2*N], bit[2*N], SIZE;
vector <int> compress;
 
int find(int x){
	int l = 0, r = compress.size() - 1, mid, ans = 0;
	while (l <= r){
		mid = l + r >> 1;
		if (compress[mid] >= x) 
			ans = mid + 1, r = mid - 1;
		else
			l = mid + 1;
	}
 
	return ans;
}
 
void upd(int idx, int val){
	while (idx > 0)
		bit[idx] = min(bit[idx], val),
		idx -= idx &-idx;
}
 
int get(int idx, int ans = 1e9){
	while (idx <= SIZE)
		ans = min(ans, bit[idx]),
		idx += idx & -idx;
	return ans;
}
int main()
{
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    // #ifndef ONLINE_JUDGE
    //     freopen(file".inp","r",stdin); freopen(file".out","w",stdout);
    // #endif
    
    cin >> n >> m;
 
    compress.push_back(0);
    for (int i = 1; i <= n; i ++){
        cin >> h[i];
        compress.push_back(h[i] - i*m);
    }
 
    compress.push_back(-(n + 1)*m);
    sort(compress.begin(), compress.end());
    SIZE = compress.size();
  	for (int i = 0; i <= n + 1000; i ++)
        dp[i] = bit[i] = 1e9;
 
    dp[0] = 0;
    upd(find(0), -1);
/*
    for (int i = 1; i <= n + 1; i ++){
        for (int j = i - 1; j >= 0; j --)
            if (h[j] - j*m >= h[i] - i*m)
                dp[i] = min(dp[i], dp[j] + i - j - 1);
        // cout << dp[i] << ' ';
    }
 
*/    
 
    for (int i = 1; i <= n + 1; i ++){
    	ll pos = find(h[i] - i*m), tmp = get(pos);
    	dp[i] = tmp + i;
 
    	upd(pos, dp[i] - i - 1);
    }
    cout << dp[n + 1];
    
 
    return 0;
}    
/**  /\_/\
    (= ._.)
    / >0  \>1 
  ________________________
 / Brainstorming section /
/=======================/
---
===
with two fixed point j, i you are allowed to change every pole between j, i (j < i)
-> could it be changed so that you can go from j->i
possible case: 
+ a[i] <= a[j]
+ h[j] + (i - j)*m >= h[i] <=> h[j] + i*m - j*m >= h[i] <=> h[j] - j*m >= h[i] - i*m
 
 
upd(h[i], dp[i] - i - 1)
get(h[j] - j*m)
 
===
**/
// Before submit: spot the visible bug by reading the code. 

Compilation message (stderr)

triusis.cpp: In function 'int find(int)':
triusis.cpp:18:11: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   18 |   mid = l + r >> 1;
      |         ~~^~~

• Subtask 1: 14 / 14
• Subtask 2: 21 / 21
• Subtask 3: 28 / 28
• Subtask 4: 37 / 37