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Submission #43367

# Submission time Handle Problem Language Result Execution time Memory
43367 2018-03-15T04:24:22 Z top34051 Boat (APIO16_boat) C++14
27 / 100
 2000 ms 8416 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]));
}

ll combi2(ll x, ll y) {
    if(x<y) return 0;
    ll res = invfac[y];
    for(ll i=x-y+1;i<=x;i++) res = mul(res, i);
//    printf("combi %lld %lld : %lld\n",x,y,res);
    return res;
}

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
	if(m>1100) exit(0);
	for(int i=1;i<=m;i++) {
        ll sz = itv[i].Y-itv[i].X+1;
        for(int use=1;use<=n;use++) temp[i][use] = combi2(sz,use);
        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:51:15: 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:97:16: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
                ^
boat.cpp:98:49: 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 2036 ms 8416 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 2036 ms 8416 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #3
27.0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 88 ms 8416 KB Output is correct
2 Correct 80 ms 8416 KB Output is correct
3 Correct 81 ms 8416 KB Output is correct
4 Correct 80 ms 8416 KB Output is correct
5 Correct 81 ms 8416 KB Output is correct
6 Correct 85 ms 8416 KB Output is correct
7 Correct 85 ms 8416 KB Output is correct
8 Correct 86 ms 8416 KB Output is correct
9 Correct 88 ms 8416 KB Output is correct
10 Correct 84 ms 8416 KB Output is correct
11 Correct 82 ms 8416 KB Output is correct
12 Correct 81 ms 8416 KB Output is correct
13 Correct 80 ms 8416 KB Output is correct
14 Correct 79 ms 8416 KB Output is correct
15 Correct 82 ms 8416 KB Output is correct
16 Correct 37 ms 8416 KB Output is correct
17 Correct 36 ms 8416 KB Output is correct
18 Correct 47 ms 8416 KB Output is correct
19 Correct 35 ms 8416 KB Output is correct
20 Correct 39 ms 8416 KB Output is correct

Subtask #4
0 / 42.0

# Verdict Execution time Memory Grader output
1 Execution timed out 2036 ms 8416 KB Time limit exceeded
2 Halted 0 ms 0 KB -