POJ-1952 最长下降子序列 + 方案数

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求最长下降子序列简单就是求方案数比较麻烦点看了别人的解题报考才懂

也对最长**子序列的理解更深一步

#include<stdio.h>#include<string.h>#include<queue>using namespace std;const int maxn = 5005;int n;int price[maxn],len[maxn],count[maxn];   //len[i]记录到i最长下降序列数  count记录方案数int maxnum,max_count;int main(){//freopen("data.in","r",stdin);while( scanf("%d",&n) != EOF ){for( int i=0; i < n; i ++ )scanf("%d",&price[i] );maxnum = -1; for( int i = 0; i < n; i++ ) {count[i] = 1;len[i] = 1;     //初始化for( int j=i-1; j>=0; j-- )//找出第i项与i-1项匹配出最长的下降序列{if( price[j] > price[i] ){if( len[j] + 1 > len[i] ){len[i] = len[j]+1;count[i] = count[j];}else if( ( len[j] + 1 ) == len[i] )//下降序列数相同 方案数相加count[i] += count[j];}else if( price[j] == price[i])//去重{if( len[i] == 1 )count[i]=0;break;}}if( len[i] > maxnum )//找出最长下降序列数maxnum = len[i];}max_count = 0;for( int i=0; i < n; i ++ )//统计方案数{if( len[i] == maxnum )max_count += count[i];}printf("%d %d\n",maxnum,max_count);}return 0;}