POJ 3264 Balanced Lineup树状数组

题意：求区间最值

思路：线段树，树状数组，RMQ。。。这里是树状数组写法

点击打开链接

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
using namespace std;
typedef long long LL;
const int maxn=2e5+5;
int lowbit(int x) {
    return x&(-x);
}
int c[maxn],c1[maxn],v[maxn],v1[maxn];
int n,m;
void add(int k,int num) {
    v[k]=num;
    v1[k]=num;
    while(k<=n) {
        c[k]=max(c[k],num);
        c1[k]=min(c1[k],num);
        k+=lowbit(k);
    }
}
int A_B(int x,int y) {
    int ans=v[y];
    while(x!=y){
        for(y-=1;y-(y&-y)>=x;y-=lowbit(y)) {
            ans=max(ans,c[y]);
        }
        ans=max(ans,v[y]);
    }
    return ans;
}
int A_B1(int x,int y) {
    int ans=v1[y];
    while(x!=y){
        for(y-=1;y-(y&-y)>=x;y-=lowbit(y)) {
            ans=min(ans,c1[y]);
        }
        ans=min(ans,v1[y]);
    }
    return ans;
}
int main() {
    int a,b;
    while(scanf("%d%d",&n,&m) != EOF) {
        memset(c,0,sizeof(c));
        memset(c1,0x3f,sizeof(c1));
        memset(v,0,sizeof(v));
        memset(v1,0,sizeof(v1));
        for(int i=1;i<=n;i++) {
            scanf("%d",&v[i]);
            add(i,v[i]);
        }
        for(int i=1;i<=m;i++) {
            int a,b;
            scanf("%d%d",&a,&b);
            int aa=A_B(a,b);
            int bb=A_B1(a,b);
            printf("%d\n",abs(aa-bb));
        }
    }
}