【DP】 HDOJ 5406 CRB and Apple

用树状数组优化DP。。。。

#include <bits/stdc++.h>using namespace std;typedef long long LL;#define lowbit(x) (x&(-x))const int maxn = 1005;int tree[maxn][maxn];pair<int, int> a[maxn];int t[maxn], y[maxn], n, cnt;int cmp(pair<int, int> aa, pair<int, int> bb){if(aa.first != bb.first) return aa.first > bb.first;return aa.second < bb.second;}void add(int x, int y, int v){for(; y <= cnt; y += lowbit(y)) tree[x][y] = max(tree[x][y], v);}int query(int x, int y){int res = 0;for(; y; y -= lowbit(y)) res = max(res, tree[x][y]);return res;}void work(){cnt = 0;scanf("%d", &n);for(int i = 1; i <= n; i++) {scanf("%d%d", &a[i].first, &a[i].second);y[cnt++] = a[i].second;}sort(y, y+cnt);cnt = unique(y, y+cnt) - y;for(int i = 1; i <= n; i++) a[i].second = lower_bound(y, y+cnt, a[i].second) - y + 1;memset(tree, 0, sizeof tree);sort(a+1, a+n+1, cmp);for(int i = 1; i <= n; i++) {for(int j = 1; j <= cnt; j++) t[j] = query(j, a[i].second) + 1;for(int j = 1; j <= cnt; j++) {add(j, a[i].second, t[j]);add(a[i].second, j, t[j]);}}int ans = 0;for(int i = 1; i <= cnt; i++) ans = max(ans, query(i, cnt));printf("%d\n", ans);}int main(){int _;scanf("%d", &_);while(_--) work();return 0;}