Light OJ 1084 线段树+dp or（单调队列+dp） 水题

2B错误，线段树开了2倍空间， 检查到死，改成4倍空间直接AC，太伤了，线段树太弱了。

线段树：

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
#define lson l, m, rt<<1
#define rson m+1, r, rt<<1|1
#define Mid int m = (l+r) >> 1;
const int maxn = 100005;
const int inf = 1e9;
int n, k;
int a[maxn];
int dp[maxn];

struct segtree {
	int sum[maxn<<2];
	void pushUp(int rt) {
        sum[rt] = min(sum[rt<<1], sum[rt<<1|1]);
	}
	void build(int l = 0, int r = n, int rt = 1) {
		sum[rt] = inf;
		if(l == r) {
		    if(l == 0) sum[rt] = 0;
		    return;
		}
		Mid;
		build(lson);
		build(rson);
		pushUp(rt);
	}
	void insert(int p, int v, int l = 0, int r = n, int rt = 1) {
		if(l == r) {
			sum[rt] = min(sum[rt], v);
			return;
		}
		Mid;
		if(p <= m) insert(p, v, lson);
		else insert(p, v, rson);
		pushUp(rt);
	}
	int query(int L, int R, int l = 0, int r = n, int rt = 1) {
		if(L <= l && r <= R)
			return sum[rt];
		Mid;
		int ret = inf;
		if(L <= m) ret = min(ret, query(L, R, lson));
		if(R > m) ret = min(ret, query(L, R, rson));
		return ret;
	}
	void print(int l = 0, int r = n, int rt = 1) {
	    if(l ==r) {
            printf("%d ", sum[rt]);
            return;
	    }
	    Mid;
	    print(lson);
	    print(rson);
	}
}T;

int main() {
   // freopen("int.txt", "r", stdin);
	int i, j, d, cas;
	scanf("%d", &cas);
	for(int ca = 1; ca <= cas; ca++) {
		scanf("%d%d", &n, &k);
		for(i = 1; i <= n; i++) {
			scanf("%d", &a[i]);
			dp[i] = inf;
		}
		T.build();
		dp[0] = 0;
		sort(a+1, a+n+1);
		for(i = 1; i <= n; i++) {
			j = lower_bound(a+1, a+i+1, a[i]-(k<<1))-a;
			//printf("i = %d j = %d\n", i, j);
			if(i-j+1 >= 3) {
			//    puts("YES");
				dp[i] = min(dp[i], T.query(j-1, i-3) + 1);
				T.insert(i, dp[i]);
			}
		}
		if(dp[n] >= inf) dp[n] = -1;
		printf("Case %d: %d\n", ca, dp[n]);
	}
	return 0;
}

单调队列：

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
#define lson l, m, rt<<1
#define rson m+1, r, rt<<1|1
#define Mid int m = (l+r) >> 1;
const int maxn = 100005;
const int inf = 1e9;
int n, k;
int a[maxn];
int dp[maxn];

int Q[maxn];
int main() {
   // freopen("int.txt", "r", stdin);
	int i, j, d, cas;
	scanf("%d", &cas);
	for(int ca = 1; ca <= cas; ca++) {
		scanf("%d%d", &n, &k);
		for(i = 1; i <= n; i++) {
			scanf("%d", &a[i]);
			dp[i] = -1;
		}
		sort(a+1, a+n+1);
		dp[0] = 0;
		int len = k<<1;

		int s = 0, e = 0;
		for(i = 1; i <= n; i++) {
			int t = i-3;
			if(t >= 0 && ~dp[t]) {
				while(s < e && dp[Q[e-1]] > dp[t]) e--;
				Q[e++] = t;
			}

			while(s < e && a[Q[s]+1] + len < a[i]) s++;
			if(s != e) dp[i] = dp[Q[s]]+1;
		}
		printf("Case %d: %d\n", ca, dp[n]);
	}
	return 0;
}