Submission #1085526

#	Time	Username	Problem	Language	Result	Execution time	Memory
1085526		Sunbae	Biochips (IZhO12_biochips)	C++17	10 / 100	2080 ms	524288 KiB

biochips

#include <bits/stdc++.h>
#define z exit(0)
using namespace std;
const int N = 2e5 + 5, inf = 2e8;
vector<int> g[N];
int x[N], tin[N], tout[N], timer = 0, V[N], dp[N][501];
void dfs(int u, int p){
	tin[u] = timer++;
	for(int v: g[u]) dfs(v, u);
	tout[u] = timer++;
}
int bit[501][N];
void upd(int k, int i, int val){ for(++i; i<N; i+=i&-i) bit[k][i] = max(bit[k][i], val);}
int qry(int k, int i){ int res = -inf; for(++i; i; i-=i&-i) res = max(res, bit[k][i]); return res;}
bool cmp(int i, int j){ return tout[i] < tout[j]; }
signed main(){
	int n, m, r = 0; scanf("%d %d", &n, &m);
	for(int v = 0, u; v<n; ++v){
		scanf("%d %d", &u, x+v); --u; 
		if(u != -1) g[u].push_back(v);
		else r = v;
		V[v] = v;
		fill(dp[v], dp[v]+m+1, -inf);
	}
	for(int k = 0; k<=m; ++k) fill(bit[k], bit[k]+m+1, -inf);
	dfs(r, r);
	sort(V, V+n, cmp);
	upd(0, 0, dp[0][0] = 0);
	upd(1, 0, dp[0][1] = x[V[0]]);
	int ans = -inf;
	for(int i = 1; i<n; ++i){
		int low = 0, high = i-1, idx = -1;
		while(low <= high){
			int mid = low + ((high-low)>>1);
			if(tout[V[mid]] < tin[V[i]]) low = mid+1, idx = mid;
			else high = mid-1;
		}
		for(int k = 0; k<=m; ++k){
			dp[i][k] = max(dp[i][k], dp[i-1][k]);
			if(idx != -1) dp[i][k] = max(dp[i][k], qry(k-1, idx) + x[V[i]]);
		}	
		for(int k = 0; k<=m; ++k) upd(k, i, dp[i][k]);
		ans = max(ans, dp[i][m]);
	}
	printf("%d", ans);
}

Compilation message (stderr)

biochips.cpp: In function 'int main()':
biochips.cpp:17:24: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   17 |  int n, m, r = 0; scanf("%d %d", &n, &m);
      |                   ~~~~~^~~~~~~~~~~~~~~~~
biochips.cpp:19:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   19 |   scanf("%d %d", &u, x+v); --u;
      |   ~~~~~^~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 100