51nod 1134 最长递增子序列

Posted 2020-08-15 GraceSkyer

题目链接：51nod 1134 最长递增子序列

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<algorithm>
 4 using namespace std;
 5 const int N = 50001;
 6 int a[N];
 7 int b[N];
 8 int Search(int num, int low, int high){
 9     int mid;
10     while(low <= high){
11         mid = (low + high)/2;
12         if(num >= b[mid]) low = mid + 1;
13         else high = mid - 1;
14     }
15     return low;
16 }
17 int DP(int n){
18     int i, len, pos;
19     b[1] = a[1];
20     len = 1;
21     for(i = 2; i <= n; i++){
22         if(a[i] >= b[len])
23             b[++len] = a[i];
24         else{
25             pos = Search(a[i],1,len);
26             //在b[]数组中找出第一个比a[i]大的位置并且让a[i]替代这个位置
27             b[pos] = a[i];
28         }
29     }
30     return len;
31 }
32 int main(){
33     int n, i, j;
34     scanf("%d", &n);
35     for(i = 1; i <= n; ++i)
36         scanf("%d", &a[i]);
37     int len = DP(n);
38     printf("%d\\n", len);
39     return 0;
40 }

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