洛谷P4704 太极剑(乱搞)

题意

题目链接

Sol

不会正解

写了发暴力过了，貌似跑的还挺快？。。

// luogu-judger-enable-o2

// luogu-judger-enable-o2

#include<bits/stdc++.h>

#define MP(x, y) make_pair(x, y)

#define fi first

#define se second

#define LL long long

template <typename A, typename B> inline bool chmin(A &a, B b){if(a > b) {a = b; return 1;} return 0;}

template <typename A, typename B> inline bool chmax(A &a, B b){if(a < b) {a = b; return 1;} return 0;}

#define getchar() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, 1<<22, stdin), p1 == p2) ? EOF : *p1++)

char buf[(1 << 22)], *p1 = buf, *p2 = buf;

using namespace std;

const int MAXN = 8e5 + 10, INF = 1e9;

const double eps = 1e-5;

inline int read() {

    char c = getchar(); int x = 0, f = 1;

    while(c < '0' || c > '9') {if(c == '-') f = -1; c = getchar();}

    while(c >= '0' && c <= '9') x = x * 10 + c - '0', c = getchar();

    return x * f;

}

int N, a[MAXN], b[MAXN], col[MAXN], out, x, y, gg = INF, ti[MAXN], ss, st[MAXN], top;

int solve(int l, int r) {

	ss++;

    int ans = 0;

    for(int i = l; i <= r; i++) {

    	if(ti[col[i]] != ss) ti[col[i]] = ss;

        else ans++, ss++;

    	if(ans >= out) return out;

	}

    return ans;

}

signed main() {

    N = read();

    for(int i = 1; i <= N; i++) {

        a[i] = read(), b[i] = read();

        if(a[i] > b[i]) swap(a[i], b[i]);

        col[a[i]] = col[a[i] + 2 * N] = i;

        col[b[i]] = col[b[i] + 2 * N] = i;

        int tmp = min(b[i] - a[i], a[i] - b[i] + 2 * N);

        if(tmp < gg) x = a[i], y = b[i], gg = tmp;

    }

    out = INF;

    for(int i = x; i <= y; i++) st[++top] = i;

    random_shuffle(st + 1, st + top + 1);

    for(int i = 1; i <= top; i++) {

    	int k = st[i];

        chmin(out, solve(k, k + 2 * N - 1));

    }

    cout << out / 2 +1;

    return 0;

}