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Submission #43372

# Submission time Handle Problem Language Result Execution time Memory
43372 2018-03-15T04:43:14 Z top34051 Boat (APIO16_boat) C++14
36 / 100
 2000 ms 14752 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 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
	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]);
	}
	//precompute
	for(int i=1;i<=m;i++) {
        ll sz = itv[i].Y-itv[i].X+1;
        for(int use=1;use<=n;use++) rec[i][use] = combi2(sz,use);
	}
}

ll solve() {
    ll res = 0;
	for(int i=0;i<=m;i++) dp[0][i] = 1;
	for(int x=1;x<=n;x++) {
		for(int i=1;i<=m;i++) {
			dp[x][i] = dp[x][i-1];
			if(a[x]<=itv[i].X && itv[i].Y<=b[x]) {
				ll cnt = 1;
				ll sz = itv[i].Y-itv[i].X+1;
				for(int y=x-1;y>=0;y--) {
					ll sum = 0;
					for(int use=1;use<=cnt;use++) sum = add(sum, mul(rec[i][use], combi1(cnt-1,use-1)));
//					printf("------- x = %d i = %d : y = %d    =>   %lld\n",x,i,y,sum);
					dp[x][i] = add(dp[x][i], mul(dp[y][i-1], sum));
					if(a[y]<=itv[i].X && itv[i].Y<=b[y]) cnt++;
				}
			}
//			printf("dp %d %d = %lld\n",x,i,dp[x][i]);
		}
		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:49:15: 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 'long long int solve()':
boat.cpp:75:8: warning: unused variable 'sz' [-Wunused-variable]
     ll sz = itv[i].Y-itv[i].X+1;
        ^
boat.cpp: In function 'int main()':
boat.cpp:92:16: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
                ^
boat.cpp:93:49: 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 744 ms 14348 KB Output is correct
2 Correct 739 ms 14348 KB Output is correct
3 Correct 738 ms 14476 KB Output is correct
4 Correct 749 ms 14496 KB Output is correct
5 Correct 737 ms 14564 KB Output is correct
6 Correct 744 ms 14564 KB Output is correct
7 Correct 734 ms 14612 KB Output is correct
8 Correct 736 ms 14644 KB Output is correct
9 Correct 737 ms 14644 KB Output is correct
10 Correct 732 ms 14644 KB Output is correct
11 Correct 738 ms 14752 KB Output is correct
12 Correct 736 ms 14752 KB Output is correct
13 Correct 732 ms 14752 KB Output is correct
14 Correct 733 ms 14752 KB Output is correct
15 Correct 733 ms 14752 KB Output is correct
16 Correct 143 ms 14752 KB Output is correct
17 Correct 155 ms 14752 KB Output is correct
18 Correct 148 ms 14752 KB Output is correct
19 Correct 155 ms 14752 KB Output is correct
20 Correct 161 ms 14752 KB Output is correct

Subtask #2
0 / 22.0

# Verdict Execution time Memory Grader output
1 Correct 744 ms 14348 KB Output is correct
2 Correct 739 ms 14348 KB Output is correct
3 Correct 738 ms 14476 KB Output is correct
4 Correct 749 ms 14496 KB Output is correct
5 Correct 737 ms 14564 KB Output is correct
6 Correct 744 ms 14564 KB Output is correct
7 Correct 734 ms 14612 KB Output is correct
8 Correct 736 ms 14644 KB Output is correct
9 Correct 737 ms 14644 KB Output is correct
10 Correct 732 ms 14644 KB Output is correct
11 Correct 738 ms 14752 KB Output is correct
12 Correct 736 ms 14752 KB Output is correct
13 Correct 732 ms 14752 KB Output is correct
14 Correct 733 ms 14752 KB Output is correct
15 Correct 733 ms 14752 KB Output is correct
16 Correct 143 ms 14752 KB Output is correct
17 Correct 155 ms 14752 KB Output is correct
18 Correct 148 ms 14752 KB Output is correct
19 Correct 155 ms 14752 KB Output is correct
20 Correct 161 ms 14752 KB Output is correct
21 Execution timed out 2033 ms 14752 KB Time limit exceeded
22 Halted 0 ms 0 KB -

Subtask #3
27.0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 150 ms 14752 KB Output is correct
2 Correct 105 ms 14752 KB Output is correct
3 Correct 134 ms 14752 KB Output is correct
4 Correct 150 ms 14752 KB Output is correct
5 Correct 167 ms 14752 KB Output is correct
6 Correct 352 ms 14752 KB Output is correct
7 Correct 340 ms 14752 KB Output is correct
8 Correct 362 ms 14752 KB Output is correct
9 Correct 364 ms 14752 KB Output is correct
10 Correct 352 ms 14752 KB Output is correct
11 Correct 159 ms 14752 KB Output is correct
12 Correct 109 ms 14752 KB Output is correct
13 Correct 111 ms 14752 KB Output is correct
14 Correct 119 ms 14752 KB Output is correct
15 Correct 144 ms 14752 KB Output is correct
16 Correct 90 ms 14752 KB Output is correct
17 Correct 75 ms 14752 KB Output is correct
18 Correct 86 ms 14752 KB Output is correct
19 Correct 78 ms 14752 KB Output is correct
20 Correct 97 ms 14752 KB Output is correct

Subtask #4
0 / 42.0

# Verdict Execution time Memory Grader output
1 Correct 744 ms 14348 KB Output is correct
2 Correct 739 ms 14348 KB Output is correct
3 Correct 738 ms 14476 KB Output is correct
4 Correct 749 ms 14496 KB Output is correct
5 Correct 737 ms 14564 KB Output is correct
6 Correct 744 ms 14564 KB Output is correct
7 Correct 734 ms 14612 KB Output is correct
8 Correct 736 ms 14644 KB Output is correct
9 Correct 737 ms 14644 KB Output is correct
10 Correct 732 ms 14644 KB Output is correct
11 Correct 738 ms 14752 KB Output is correct
12 Correct 736 ms 14752 KB Output is correct
13 Correct 732 ms 14752 KB Output is correct
14 Correct 733 ms 14752 KB Output is correct
15 Correct 733 ms 14752 KB Output is correct
16 Correct 143 ms 14752 KB Output is correct
17 Correct 155 ms 14752 KB Output is correct
18 Correct 148 ms 14752 KB Output is correct
19 Correct 155 ms 14752 KB Output is correct
20 Correct 161 ms 14752 KB Output is correct
21 Execution timed out 2033 ms 14752 KB Time limit exceeded
22 Halted 0 ms 0 KB -