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;
}