{"id":269,"date":"2010-05-31T12:38:00","date_gmt":"2010-05-31T04:38:00","guid":{"rendered":"http:\/\/localhost\/?p=269"},"modified":"2010-05-31T12:38:00","modified_gmt":"2010-05-31T04:38:00","slug":"netease_youdao_qualifying_-_the_largest_and_subsequence","status":"publish","type":"post","link":"https:\/\/www.shuizilong.com\/wjmzbmr\/?p=269","title":{"rendered":"\u7f51\u6613\u6709\u9053\u8d44\u683c\u8d5b1-\u6700\u5927\u548c\u5b50\u5e8f\u5217"},"content":{"rendered":"

\u6211\u4e2aNC\u3002\u3002\u8fd9\u9053\u9898\u4ee3\u7801\u91cf\u5b9e\u9645\u4e0a\u5f88\u5c0f\u800c\u4e14\u4e5f\u4e0d\u662f\u5f88triky\u3002\u3002\u6bd4\u8d5b\u7684\u65f6\u5019\u6211\u5c45\u7136\u60b2\u5267\u56e7\u6b7b\u4e86\u3002\u3002\u3002\u3002
\u5c31\u662f\u539f\u6765\u7684\u7b97\u6cd5\uff0c\u9996\u5148\u7531\u4e8e\u6bcf\u4e2a\u90fd\u662f\u975e\u7a7a\u7684\u90a3\u4e48\u7279\u5224\u4e00\u4e0b\u6b63\u6570\u5c0f\u4e8e\u7b49\u4e8e2\u4e2a\u60c5\u51b5\uff08\u6b64\u65f6\u663e\u7136\u53d6\u6700\u5927\u7684\u4e24\u4e2a\uff09\u3002\u3002\u7136\u540e\u5148\u7b97\u6ca1\u6709\u8de8\u8d8a\u73af\u7684\uff0c\u8bbeL[x]\u8868\u793a1-x\u7684\u6700\u5927\u5b50\u5e8f\u5217\u957f\u5ea6,R[x]\u8868\u793ax-n\u7684\u6700\u5927\u5b50\u5e8f\u5217\u957f\u5ea6\uff0c\u7b54\u6848\u5f88\u663e\u7136\u5c31\u662fMax(L[x]+R[x+1])\u3002\u3002\u3002\u7136\u540e\u5982\u679c\u8de8\u8d8a\u73af\u4e86\uff0c\u90a3\u4e48\u5b83\u7684\u5bf9\u5076\u95ee\u9898\u5c31\u662f\u4e0d\u9009\u7684\u90a3\u4e9b\u80af\u5b9a\u4e0d\u8de8\u8d8a\u73af\uff0c\u4e00\u6837\u7684DP\u53ef\u4ee5\u7b97\u51fa\u6765\uff08\u4e3a\u4e86\u65b9\u4fbf\u628a\u6240\u6709\u503c\u53d6\u8d1f\u5c31OK\u4e86\u3002\u3002\uff09\u3002\u3002\u4e24\u4e2a\u4e2d\u7684\u6700\u5927\u503c\u5c31\u662f\u7b54\u6848\u4e86\u3002\u3002\u3002\u3002
Code\uff1a
#include<cstdio>#include<algorithm>#define rep(i,n) for(int i=0;i<n;i++)using namespace std;const int maxn=50000+10,inf=~0U>>1;int t,n,A[maxn],L[maxn],R[maxn];int Cal(){ L[0]=0; for(int i=1;i<=n;i++) L[i]=max(L[i-1],0)+A[i]; R[n+1]=0; for(int i=n;i>=1;i–) R[i]=max(R[i+1],0)+A[i]; for(int i=1;i<=n;i++)L[i]=max(L[i],L[i-1]); for(int i=n;i>=1;i–)R[i]=max(R[i],R[i+1]); int ans=-inf; for(int i=1;i<=n;i++)ans=max(ans,L[i]+R[i+1]); return ans;}void Solve(){ scanf("%d",&n);int z=0,s=0,a=-inf,b=-inf; rep(i,n)scanf("%d",A+i+1),z+=A[i+1]>0,s+=A[i+1]; if(z<=2) { rep(i,n) { if(A[i+1]>b)b=A[i+1]; if(a<b)swap(a,b); } printf("%dn",a+b); return; } int ans=Cal(); rep(i,n)A[i+1]=-A[i+1]; ans=max(ans,s+Cal()); printf("%dn",ans);}int main(){ \/\/freopen("in","r",stdin); int t;scanf("%d",&t); rep(i,t)Solve();} <\/p>\n","protected":false},"excerpt":{"rendered":"

\u6211\u4e2aNC\u3002\u3002\u8fd9\u9053\u9898\u4ee3\u7801\u91cf\u5b9e\u9645\u4e0a\u5f88\u5c0f\u800c\u4e14\u4e5f\u4e0d\u662f\u5f88triky\u3002\u3002\u6bd4\u8d5b\u7684\u65f6\u5019\u6211\u5c45\u7136\u60b2\u5267\u56e7\u6b7b\u4e86\u3002\u3002\u3002\u3002\u5c31\u662f\u539f\u6765\u7684\u7b97\u6cd5\uff0c\u9996\u5148\u7531\u4e8e\u6bcf\u4e2a\u90fd\u662f\u975e\u7a7a\u7684\u90a3\u4e48\u7279\u5224\u4e00\u4e0b\u6b63\u6570\u5c0f\u4e8e\u7b49\u4e8e2\u4e2a\u60c5\u51b5\uff08\u6b64\u65f6\u663e\u7136\u53d6\u6700\u5927\u7684\u4e24\u4e2a\uff09\u3002\u3002\u7136\u540e\u5148\u7b97\u6ca1\u6709\u8de8\u8d8a\u73af\u7684\uff0c\u8bbeL[x]\u8868\u793a1-x\u7684\u6700\u5927\u5b50\u5e8f\u5217\u957f\u5ea6,R[x]\u8868\u793ax-n\u7684\u6700\u5927\u5b50\u5e8f\u5217\u957f\u5ea6\uff0c\u7b54\u6848\u5f88\u663e\u7136\u5c31\u662fMax(L[x]+R[x+1])\u3002\u3002\u3002\u7136\u540e\u5982\u679c\u8de8\u8d8a\u73af\u4e86\uff0c\u90a3\u4e48\u5b83\u7684\u5bf9\u5076\u95ee\u9898\u5c31\u662f\u4e0d\u9009\u7684\u90a3\u4e9b\u80af\u5b9a\u4e0d\u8de8\u8d8a\u73af\uff0c\u4e00\u6837\u7684DP\u53ef\u4ee5\u7b97\u51fa\u6765\uff08\u4e3a\u4e86\u65b9\u4fbf\u628a\u6240\u6709\u503c\u53d6\u8d1f\u5c31OK\u4e86\u3002\u3002\uff09\u3002\u3002\u4e24\u4e2a\u4e2d\u7684\u6700\u5927\u503c\u5c31\u662f\u7b54\u6848\u4e86\u3002\u3002\u3002\u3002Code\uff1a#include<cstdio>#include<algorithm>#define rep(i,n) for(int i=0;i<n;i++)using namespace std;const int maxn=50000+10,inf=~0U>>1;int t,n,A[maxn],L[maxn],R[maxn];int Cal(){ L[0]=0; for(int i=1;i<=n;i++) L[i]=max(L[i-1],0)+A[i]; R[n+1]=0; for(int i=n;i>=1;i–) R[i]=max(R[i+1],0)+A[i]; for(int i=1;i<=n;i++)L[i]=max(L[i],L[i-1]); for(int i=n;i>=1;i–)R[i]=max(R[i],R[i+1]); int ans=-inf; for(int i=1;i<=n;i++)ans=max(ans,L[i]+R[i+1]); return ans;}void Solve(){ scanf("%d",&n);int z=0,s=0,a=-inf,b=-inf; rep(i,n)scanf("%d",A+i+1),z+=A[i+1]>0,s+=A[i+1]; if(z<=2) { rep(i,n) { if(A[i+1]>b)b=A[i+1]; if(a<b)swap(a,b); } printf("%dn",a+b); return; } int ans=Cal(); rep(i,n)A[i+1]=-A[i+1]; ans=max(ans,s+Cal()); printf("%dn",ans);}int main(){ \/\/freopen("in","r",stdin); int t;scanf("%d",&t); rep(i,t)Solve();}<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[10],"tags":[],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/posts\/269"}],"collection":[{"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=269"}],"version-history":[{"count":0,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/posts\/269\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=269"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=269"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=269"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}