44 lines
1.0 KiB
C++
44 lines
1.0 KiB
C++
#include <cstdio>
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#include <cstring>
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#include <cstdlib>
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#include <cmath>
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#include <algorithm>
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#include <iostream>
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#define INF 0x3f3f3f3f
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#define MAXN 1000005
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using namespace std;
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int N, dp[MAXN];
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struct Node {
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int x, y, ac;
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}e[5005];
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int DP() {
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int ret = INF;
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memset(dp, 0x3f, sizeof (dp));
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dp[e[1].x] = 0;
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for (int i = 2; i <= N; ++i) {
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int a = e[i].ac, b = e[i].x;
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for (int j = a; j < b; ++j) {
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int p = 2*e[i].x-j;
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if (p < e[N].x) {
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dp[p] = min(dp[p], dp[j]+1);
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} else {
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ret = min(ret, dp[j]+1);
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}
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}
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}
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return ret == INF ? -1 : ret;
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}
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int main() {
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int T;
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scanf("%d", &T);
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while (T--) {
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scanf("%d", &N);
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for (int i = 1; i <= N; ++i) {
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scanf("%d %d", &e[i].x, &e[i].y);
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e[i].ac = max(0, (int)ceil(e[i].x-sqrt(2.*e[i].y*e[1].y-1.*e[1].y*e[1].y)));
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}
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printf("%d\n", DP());
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}
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return 0;
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}
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