1 #include <iostream>
2 #include <cstdio>
3 #include <cstring>
4 #include <algorithm>
5 #include <map>
6 #define MP make_pair
7 using namespace std;
8
9 typedef pair<int, int> PII;
10
11 const int maxn = 1000 + 10;
12 const int INF = 0x3f3f3f3f;
13
14 PII a[maxn];
15 int sum[maxn];
16
17 int n, v, x;
18
19 int d[maxn][maxn][2];
20
21 int main()
22 {
23 while(scanf("%d%d%d", &n, &v, &x) == 3)
24 {
25 for(int i = 1; i <= n; i++) scanf("%d%d", &a[i].first, &a[i].second);
26 a[++n] = MP(x, 0);
27 sort(a + 1, a + 1 + n);
28 for(int i = 1; i <= n; i++) sum[i] = sum[i - 1] + a[i].second;
29
30 int p;
31 for(int i = 1; i <= n; i++) if(a[i].first == x) { p = i; break; }
32 memset(d, 0x3f, sizeof(d));
33 d[p][p][0] = d[p][p][1] = 0;
34
35 for(int i = p; i > 0; i--)
36 for(int j = p; j <= n; j++)
37 {
38 if(i == j) continue;
39 int t = sum[i - 1] + sum[n] - sum[j];
40
41 int& ans1 = d[i][j][0];
42 ans1 = min(ans1, d[i+1][j][0] + (t + a[i].second) * (a[i+1].first - a[i].first));
43 ans1 = min(ans1, d[i+1][j][1] + (t + a[i].second) * (a[j].first - a[i].first));
44
45 int& ans2 = d[i][j][1];
46 ans2 = min(ans2, d[i][j-1][0] + (t + a[j].second) * (a[j].first - a[i].first));
47 ans2 = min(ans2, d[i][j-1][1] + (t + a[j].second) * (a[j].first - a[j-1].first));
48 }
49
50 printf("%d\n", min(d[1][n][0], d[1][n][1]) * v);
51 }
52
53 return 0;
54 }
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