This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> pii;
typedef long long ll;
const int MAXN = 3e4;
const ll INF = 4e18+10;
int N, M, X;
vector<int> v[MAXN];
bool ok[MAXN];
ll dp[MAXN];
// int d[MAXN];
ll f(int cur) {
if (dp[cur] != -1) return dp[cur];
dp[cur] = INF;
for (int dx : v[cur]) {
int i = cur - dx, cnt = 1;
while (i > 0)
dp[cur] = min(dp[cur], f(i) + cnt),
i -= dx, cnt++;
i = cur + dx, cnt = 1;
while (i < N)
dp[cur] = min(dp[cur], f(i) + cnt),
i += dx, cnt++;
}
return dp[cur];
}
// int dijkstra() {
// for (int i = 0; i < N; i++) d[i] = INF;
// d[0] = 0;
// int cur = 0;
// while (true) {
// ok[cur] = true;
// for (int dx : v[cur]) {
// printf("%d-%d\n",cur,dx);
// int i = cur - dx, cnt = 1;
// while (i > 0)
// d[i] = min(d[i], d[cur] + (cur - i)/dx),
// i -= dx, cnt++;
// i = cur + dx, cnt = 1;
// while (i < N)
// d[i] = min(d[i], d[cur] + cnt),
// i += dx, cnt++;
// }
// for (int i = 1; i < N; i++)
// if (cur == -1 || d[i] < d[cur])
// if (!ok[cur])
// cur = i;
// if (cur == -1) break;
// }
// return d[1];
// }
int main()
{
scanf("%d %d", &N, &M);
int X, Y;
for (int i = 0,a,b; i < M; i++) {
scanf("%d %d", &a, &b);
if (i == 0) X = a;
else if (i == 1) Y = a;
if (b != 0)
v[a].push_back(b);
}
memset(dp, -1, sizeof(dp));
dp[Y] = 0;
ll ans = f(X);
printf("%lld\n", ans < INF ? ans : -1);
}
Compilation message (stderr)
skyscraper.cpp: In function 'int main()':
skyscraper.cpp:67:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d %d", &N, &M);
^
skyscraper.cpp:70:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d %d", &a, &b);
^
skyscraper.cpp:80:11: warning: 'Y' may be used uninitialized in this function [-Wmaybe-uninitialized]
dp[Y] = 0;
^
skyscraper.cpp:68:6: warning: 'X' may be used uninitialized in this function [-Wmaybe-uninitialized]
int X, Y;
^
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