ST算法

ST算法
/*********************************
title:          poj1185
http://acm.nyist.net/JudgeOnline/problem.php?pid=119 problem: 士兵杀敌(三) algorithm: ST time: 2012-7-23 write : HuHanwu ********************************
*/ #include <iostream> #include <cstdio> #include <cmath> #define max(a,b) (a>b?a:b) #define min(a,b) (a<b?a:b) #define MN 100005 using namespace std; int mi[MN][20],mx[MN][20],w[MN]; int n,q; void rmqinit() { int i,j,m; for(i=1;i<=n;i++){mi[i][0]=mx[i][0]=w[i];} m=floor(log((double)n)/log(2.0)); for(i=1;i<=m;i++) for(j=n;j>=1;j--){ mx[j][i]=mx[j][i-1]; if(j+(1<<(i-1))<=n)mx[j][i]=max(mx[j][i],mx[j+(1<<(i-1))][i-1]); mi[j][i]=mi[j][i-1]; if(j+(1<<(i-1)<=n))mi[j][i]=min(mi[j][i],mi[j+(1<<(i-1))][i-1]); } } int rmqmin(int l,int r) { int m=floor(log((double)(r-l+1))/log(2.0)); return min(mi[l][m],mi[r-(1<<m)+1][m]); } int rmqmax(int l,int r) { int m=floor(log((double)(r-l+1))/log(2.0)); return max(mx[l][m],mx[r-(1<<m)+1][m]); } int main() { scanf("%d%d",&n,&q); for(int i=1;i<=n;i++)scanf("%d",&w[i]); rmqinit(); int l,r; for(int i=1;i<=q;i++){ scanf("%d%d",&l,&r); printf("%d\n",rmqmax(l,r)-rmqmin(l,r)); } return 0; }
posted @ 2012-08-03 16:44  huhanwu  阅读(169)  评论(0编辑  收藏  举报