HDU 1025 Constructing Roads In JGShining's Kingdom

说了一大堆，其实就是求一个最长上升子序列，二分优化到nlogn就不会超时啦

 

#include <cstdio>#include <cstring>#include <algorithm>#include <climits>using namespace std;const int maxn = 500000 + 5;const int INF = INT_MAX / 2;int top[maxn],r[maxn];int main() {    int n,kase = 0,a,b;    while(~scanf("%d",&n)) {        printf("Case %d:\n",++kase);        int ans = -1;        top[0] = 0;        for(int i = 1;i <= n;i++) {            scanf("%d%d",&a,&b);            r[a] = b; top[i] = INF;        }        for(int i = 1;i <= n;i++) {            int k = lower_bound(top + 1,top + 1 + n,r[i]) - top;            top[k] = r[i];            ans = max(k,ans);        }        printf("My king, at most %d road%s can be built.\n\n",ans,(ans > 1 ? "s" : ""));    }    return 0;}