rmq算法模板

//RMQ|模板，求区间最大数最小数之差，n是数组，q是区间个数，#include<iostream>#include<cmath>using namespace std;const int maxn=50001;int h[maxn];int mx[maxn][16],mn[maxn][16];int n,q;int max(int x,int y){return x>y?x:y;}int min(int x,int y){return x<y?x:y;}void rmq_init(){int i,j;for(j=1;j<=n;j++)mx[j][0]=mn[j][0]=h[j];int m=floor(log((double)n)/log(2.0));for(i=1;i<=m;i++){for(j=n;j>0;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]);}}for(i=1;i<=m;i++){for(j=n;j>0;j--){mn[j][i]=mn[j][i-1];if(j+(1<<(i-1))<=n)mn[j][i]=min(mn[j][i],mn[j+(1<<(i-1))][i-1]);}}}int rmq(int l,int r){int m=floor(log((double)(r-l+1))/log(2.0));int a=max(mx[l][m],mx[r-(1<<m)+1][m]);int b=min(mn[l][m],mn[r-(1<<m)+1][m]);return a-b; }int main(){int i,l,r;scanf("%d%d",&n,&q);for(i=1;i<=n;i++)scanf("%d",&h[i]);rmq_init();for(i=0;i<q;i++){scanf("%d%d",&l,&r);printf("%d\n",rmq(l,r));}return 0;}