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Submission #43374

# Submission time Handle Problem Language Result Execution time Memory
43374 2018-03-15T04:48:23 Z top34051 Boat (APIO16_boat) C++14
36 / 100
 2000 ms 26588 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], comb[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
	for(int i=1;i<=n;i++) {
		pos.push_back(a[i]);
		pos.push_back(b[i]+1);
	}
	sort(pos.begin(),pos.end());
	pos.erase(unique(pos.begin(),pos.end()),pos.end());
	for(int i=0;i<pos.size()-1;i++) itv[++m] = {pos[i],pos[i+1]-1};
//	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]);
	}
	for(int i=0;i<=n;i++) for(int j=0;j<=n;j++) comb[i][j] = combi1(i,j);
	//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)));
	}
//	printf("m = %d\n",m);
	for(int i=1;i<=m;i++) {
        for(int cnt=1;cnt<=n;cnt++) {
//            if(cnt==1) printf("calc %d %d\n",i,cnt);
        	for(int use=1;use<=cnt;use++) rec[i][cnt] = add(rec[i][cnt], mul(temp[i][use], comb[cnt-1][use-1]));
		}
	}
}

ll solve() {
    ll res = 0;
	for(int i=0;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:42:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<pos.size()-1;i++) itv[++m] = {pos[i],pos[i+1]-1};
               ^
boat.cpp: In function 'int main()':
boat.cpp:90:16: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
                ^
boat.cpp:91:49: 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
9.0 / 9.0

# Verdict Execution time Memory Grader output
1 Correct 1561 ms 26296 KB Output is correct
2 Correct 1526 ms 26336 KB Output is correct
3 Correct 1536 ms 26436 KB Output is correct
4 Correct 1522 ms 26448 KB Output is correct
5 Correct 1557 ms 26504 KB Output is correct
6 Correct 1534 ms 26504 KB Output is correct
7 Correct 1510 ms 26504 KB Output is correct
8 Correct 1529 ms 26504 KB Output is correct
9 Correct 1534 ms 26504 KB Output is correct
10 Correct 1511 ms 26508 KB Output is correct
11 Correct 1537 ms 26508 KB Output is correct
12 Correct 1501 ms 26508 KB Output is correct
13 Correct 1520 ms 26588 KB Output is correct
14 Correct 1526 ms 26588 KB Output is correct
15 Correct 1546 ms 26588 KB Output is correct
16 Correct 291 ms 26588 KB Output is correct
17 Correct 291 ms 26588 KB Output is correct
18 Correct 279 ms 26588 KB Output is correct
19 Correct 294 ms 26588 KB Output is correct
20 Correct 283 ms 26588 KB Output is correct

Subtask #2
0 / 22.0

# Verdict Execution time Memory Grader output
1 Correct 1561 ms 26296 KB Output is correct
2 Correct 1526 ms 26336 KB Output is correct
3 Correct 1536 ms 26436 KB Output is correct
4 Correct 1522 ms 26448 KB Output is correct
5 Correct 1557 ms 26504 KB Output is correct
6 Correct 1534 ms 26504 KB Output is correct
7 Correct 1510 ms 26504 KB Output is correct
8 Correct 1529 ms 26504 KB Output is correct
9 Correct 1534 ms 26504 KB Output is correct
10 Correct 1511 ms 26508 KB Output is correct
11 Correct 1537 ms 26508 KB Output is correct
12 Correct 1501 ms 26508 KB Output is correct
13 Correct 1520 ms 26588 KB Output is correct
14 Correct 1526 ms 26588 KB Output is correct
15 Correct 1546 ms 26588 KB Output is correct
16 Correct 291 ms 26588 KB Output is correct
17 Correct 291 ms 26588 KB Output is correct
18 Correct 279 ms 26588 KB Output is correct
19 Correct 294 ms 26588 KB Output is correct
20 Correct 283 ms 26588 KB Output is correct
21 Execution timed out 2013 ms 26588 KB Time limit exceeded
22 Halted 0 ms 0 KB -

Subtask #3
27.0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 22 ms 26588 KB Output is correct
2 Correct 22 ms 26588 KB Output is correct
3 Correct 22 ms 26588 KB Output is correct
4 Correct 22 ms 26588 KB Output is correct
5 Correct 23 ms 26588 KB Output is correct
6 Correct 32 ms 26588 KB Output is correct
7 Correct 25 ms 26588 KB Output is correct
8 Correct 28 ms 26588 KB Output is correct
9 Correct 25 ms 26588 KB Output is correct
10 Correct 25 ms 26588 KB Output is correct
11 Correct 22 ms 26588 KB Output is correct
12 Correct 23 ms 26588 KB Output is correct
13 Correct 22 ms 26588 KB Output is correct
14 Correct 21 ms 26588 KB Output is correct
15 Correct 22 ms 26588 KB Output is correct
16 Correct 17 ms 26588 KB Output is correct
17 Correct 14 ms 26588 KB Output is correct
18 Correct 15 ms 26588 KB Output is correct
19 Correct 15 ms 26588 KB Output is correct
20 Correct 17 ms 26588 KB Output is correct

Subtask #4
0 / 42.0

# Verdict Execution time Memory Grader output
1 Correct 1561 ms 26296 KB Output is correct
2 Correct 1526 ms 26336 KB Output is correct
3 Correct 1536 ms 26436 KB Output is correct
4 Correct 1522 ms 26448 KB Output is correct
5 Correct 1557 ms 26504 KB Output is correct
6 Correct 1534 ms 26504 KB Output is correct
7 Correct 1510 ms 26504 KB Output is correct
8 Correct 1529 ms 26504 KB Output is correct
9 Correct 1534 ms 26504 KB Output is correct
10 Correct 1511 ms 26508 KB Output is correct
11 Correct 1537 ms 26508 KB Output is correct
12 Correct 1501 ms 26508 KB Output is correct
13 Correct 1520 ms 26588 KB Output is correct
14 Correct 1526 ms 26588 KB Output is correct
15 Correct 1546 ms 26588 KB Output is correct
16 Correct 291 ms 26588 KB Output is correct
17 Correct 291 ms 26588 KB Output is correct
18 Correct 279 ms 26588 KB Output is correct
19 Correct 294 ms 26588 KB Output is correct
20 Correct 283 ms 26588 KB Output is correct
21 Execution timed out 2013 ms 26588 KB Time limit exceeded
22 Halted 0 ms 0 KB -