【重做】导弹拦截（单调栈优化dp）

二分函数很容易写错（理解问题），需要仔细想一想。

#include<bits/stdc++.h>
#define rep(i,a,n) for(register int i = a;i <= n;++i)
#define per(i,n,a) for(register int i = n;i <= a;--i)
#define lb lower_bound
#define ub upper_bound
#define mid (l+r>>1)
using namespace std;
typedef long long ll;

const int Maxn = 1e5+10; 

char c,l;

ll read(){
   ll a = 0;c = getchar(),l = c;
   while(c < '0'||c > '9')l = c,c = getchar();
   while('0' <= c&&c <= '9')a = a*10+c-'0',c = getchar();
   if(l == '-')return -a;return a;
}

int a[Maxn],sx[Maxn];
int n,top;

int work1(int x){
    int l = 1,r = top,ans = 1;
    while(l <= r)
        if(sx[mid] < x)ans = mid,r = mid-1;
        else l = mid+1;
    return ans;
}

int work2(int x){
    int l = 1,r = top,ans = 1;
    while(l <= r)
        if(sx[mid] >= x)ans = mid,r = mid-1;
        else l = mid+1;
    return ans;
}

int main(){
//    while(c != '
')a[++n] = read();
    while(cin >> a[++n]);n--;
    top = 1,sx[1] = a[1];
    rep(i,2,n){
        if(a[i] <= sx[top])sx[++top] = a[i];
        else sx[work1(a[i])] = a[i];
    }
    printf("%d
",top);
    
    top = 1,sx[1] = a[1];
    rep(i,2,n)
        if(a[i] > sx[top])sx[++top] = a[i];
        else sx[work2(a[i])] = a[i];
    printf("%d
",top);
return 0;
}