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Submission #43364

# Submission time Handle Problem Language Result Execution time Memory
43364 2018-03-15T04:15:18 Z top34051 Boat (APIO16_boat) C++14
27 / 100
 2000 ms 10888 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
	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][use] = 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;
				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(temp[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));
//					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 'long long int solve()':
boat.cpp:83:8: warning: unused variable 'sz' [-Wunused-variable]
     ll sz = itv[i].Y-itv[i].X+1;
        ^
boat.cpp: In function 'int main()':
boat.cpp:101:16: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
                ^
boat.cpp:102:49: 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 2052 ms 10888 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 2052 ms 10888 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #3
27.0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 319 ms 10888 KB Output is correct
2 Correct 249 ms 10888 KB Output is correct
3 Correct 293 ms 10888 KB Output is correct
4 Correct 330 ms 10888 KB Output is correct
5 Correct 364 ms 10888 KB Output is correct
6 Correct 719 ms 10888 KB Output is correct
7 Correct 724 ms 10888 KB Output is correct
8 Correct 710 ms 10888 KB Output is correct
9 Correct 731 ms 10888 KB Output is correct
10 Correct 746 ms 10888 KB Output is correct
11 Correct 335 ms 10888 KB Output is correct
12 Correct 235 ms 10888 KB Output is correct
13 Correct 255 ms 10888 KB Output is correct
14 Correct 278 ms 10888 KB Output is correct
15 Correct 324 ms 10888 KB Output is correct
16 Correct 144 ms 10888 KB Output is correct
17 Correct 124 ms 10888 KB Output is correct
18 Correct 141 ms 10888 KB Output is correct
19 Correct 122 ms 10888 KB Output is correct
20 Correct 172 ms 10888 KB Output is correct

Subtask #4
0 / 42.0

# Verdict Execution time Memory Grader output
1 Execution timed out 2052 ms 10888 KB Time limit exceeded
2 Halted 0 ms 0 KB -