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Submission #43366

# Submission time Handle Problem Language Result Execution time Memory
43366 2018-03-15T04:19:53 Z top34051 Boat (APIO16_boat) C++14
27 / 100
 2000 ms 8008 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][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;
				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 2013 ms 8008 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 2013 ms 8008 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #3
27.0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 83 ms 8008 KB Output is correct
2 Correct 81 ms 8008 KB Output is correct
3 Correct 81 ms 8008 KB Output is correct
4 Correct 84 ms 8008 KB Output is correct
5 Correct 82 ms 8008 KB Output is correct
6 Correct 88 ms 8008 KB Output is correct
7 Correct 90 ms 8008 KB Output is correct
8 Correct 86 ms 8008 KB Output is correct
9 Correct 86 ms 8008 KB Output is correct
10 Correct 87 ms 8008 KB Output is correct
11 Correct 83 ms 8008 KB Output is correct
12 Correct 81 ms 8008 KB Output is correct
13 Correct 80 ms 8008 KB Output is correct
14 Correct 81 ms 8008 KB Output is correct
15 Correct 82 ms 8008 KB Output is correct
16 Correct 37 ms 8008 KB Output is correct
17 Correct 37 ms 8008 KB Output is correct
18 Correct 37 ms 8008 KB Output is correct
19 Correct 36 ms 8008 KB Output is correct
20 Correct 40 ms 8008 KB Output is correct

Subtask #4
0 / 42.0

# Verdict Execution time Memory Grader output
1 Execution timed out 2013 ms 8008 KB Time limit exceeded
2 Halted 0 ms 0 KB -