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Submission #43369

# Submission time Handle Problem Language Result Execution time Memory
43369 2018-03-15T04:28:20 Z top34051 Boat (APIO16_boat) C++14
27 / 100
 2000 ms 9648 KB 
#include<bits/stdc++.h>
using namespace std;

#define ll long long
#define pii pair<int, int>
#define X first
#define Y second

const int maxn = 2e3 + 5;
const ll mod = 1e9 + 7;

int n,m;
int a[maxn], b[maxn];

vector<int> pos;
pii itv[maxn];
ll temp[maxn][maxn];
ll rec[maxn][maxn];

ll dp[maxn][maxn];

ll fac[maxn], invfac[maxn];

ll add(ll x, ll y) { return ((x+y)%mod + mod)%mod; }

ll mul(ll x, ll y) { return ((x*y)%mod + mod)%mod; }

ll inv(ll x, ll y) { return 1<x ? y - inv(y%x, x)*y/x : 1; }

ll combi1(ll x, ll y) {
    return x<y ? 0 : mul(fac[x], mul(invfac[y], invfac[x-y]));
}

void init() {
	//get interval
	pos.push_back(0); pos.push_back(2e9);
	for(int i=1;i<=n;i++) {
		pos.push_back(a[i]);
		pos.push_back(b[i]);
	}
	sort(pos.begin(),pos.end());
	pos.erase(unique(pos.begin(),pos.end()),pos.end());
	for(int i=0;i<pos.size();i++) {
		if(i!=0 && pos[i-1]+1<=pos[i]-1) itv[++m] = {pos[i-1]+1,pos[i]-1};
		itv[++m] = {pos[i],pos[i]};
	}
//	for(int i=1;i<=m;i++) printf("[%d, %d] ",itv[i].X,itv[i].Y);
//	printf("\n");
	//fac and invfac
	fac[0] = 1; invfac[0] = inv(fac[0], mod);
//    printf("fac %d = %lld inv = %lld\n",1,fac[1],invfac[1]);
	for(int i=1;i<=m;i++) {
		fac[i] = mul(fac[i-1], i);
		invfac[i] = inv(fac[i], mod);
//		printf("fac %d = %lld inv = %lld\n",i,fac[i],invfac[i]);
	}
	//precompute
	for(int i=1;i<=m;i++) {
        ll sz = itv[i].Y-itv[i].X+1;
        temp[i][1] = sz;
        for(int use=2;use<=n;use++) temp[i][use] = mul(temp[i][use-1], mul(sz-use+1, inv(use,mod)));
        for(int cnt=1;cnt<=n;cnt++) {
        	for(int use=1;use<=cnt;use++) rec[i][cnt] = add(rec[i][cnt], mul(temp[i][use], combi1(cnt-1,use-1)));
		}
	}
}

ll solve() {
    ll res = 0;
	for(int i=1;i<=m;i++) dp[0][i] = 1;
	for(int i=1;i<=m;i++) {
		for(int x=1;x<=n;x++) {
			dp[x][i] = dp[x][i-1];
			if(a[x]<=itv[i].X && itv[i].Y<=b[x]) {
				ll cnt = 1;
				for(int y=x-1;y>=0;y--) {
					dp[x][i] = add(dp[x][i], mul(dp[y][i-1], rec[i][cnt]));
					if(a[y]<=itv[i].X && itv[i].Y<=b[y]) cnt++;
				}
			}
//			printf("dp %d %d = %lld\n",x,i,dp[x][i]);
		}
	}
	for(int x=1;x<=n;x++) res = add(res, dp[x][m]);
	return res;
}

int main() {
	scanf("%d",&n);
	for(int i=1;i<=n;i++) scanf("%d%d",&a[i],&b[i]);
	init();
	printf("%lld",solve());
}

Compilation message

boat.cpp: In function 'void init()':
boat.cpp:43:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<pos.size();i++) {
               ^
boat.cpp: In function 'int main()':
boat.cpp:89:16: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
                ^
boat.cpp:90:49: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(int i=1;i<=n;i++) scanf("%d%d",&a[i],&b[i]);
                                                 ^

Subtask #1
0 / 9.0

# Verdict Execution time Memory Grader output
1 Execution timed out 2051 ms 9648 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #2
0 / 22.0

# Verdict Execution time Memory Grader output
1 Execution timed out 2051 ms 9648 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #3
27.0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 73 ms 9648 KB Output is correct
2 Correct 72 ms 9648 KB Output is correct
3 Correct 74 ms 9648 KB Output is correct
4 Correct 74 ms 9648 KB Output is correct
5 Correct 78 ms 9648 KB Output is correct
6 Correct 78 ms 9648 KB Output is correct
7 Correct 78 ms 9648 KB Output is correct
8 Correct 99 ms 9648 KB Output is correct
9 Correct 78 ms 9648 KB Output is correct
10 Correct 78 ms 9648 KB Output is correct
11 Correct 72 ms 9648 KB Output is correct
12 Correct 71 ms 9648 KB Output is correct
13 Correct 76 ms 9648 KB Output is correct
14 Correct 73 ms 9648 KB Output is correct
15 Correct 72 ms 9648 KB Output is correct
16 Correct 33 ms 9648 KB Output is correct
17 Correct 33 ms 9648 KB Output is correct
18 Correct 33 ms 9648 KB Output is correct
19 Correct 40 ms 9648 KB Output is correct
20 Correct 34 ms 9648 KB Output is correct

Subtask #4
0 / 42.0

# Verdict Execution time Memory Grader output
1 Execution timed out 2051 ms 9648 KB Time limit exceeded
2 Halted 0 ms 0 KB -