UVA-1400 Ray, Pass me the dishes!

#define _CRT_SECURE_NO_DEPRECATE
#include <iostream>
#include <string>
#include <cstring>
#include <map>
#include <algorithm>
using namespace std;
#define INF 0x3f3f3f3f
#define MAX 0x7ffffffffffffff
typedef long long ll;
const int N_MAX = 500000+20;
int D[N_MAX];
ll presum[N_MAX];
int n, m;
struct MAX_sum {
    ll data;int L, R;
    MAX_sum(ll data = 0, int L = 0, int R = 0) :data(data), L(L), R(R) {}
}max_sum[2 * N_MAX];
struct MAX_prefix {
    ll data;int R;
    MAX_prefix(ll data = 0, int R = 0) :data(data), R(R) {}
}max_prefix[2 * N_MAX];
struct MAX_suffix {
    ll data;int L;
    MAX_suffix(ll data = 0, int L = 0) :data(data), L(L) {}
}max_suffix[2 * N_MAX];

ll sum(int l,int r) {//计算区间[l,r)的和
    if (l == 0)return presum[r-1];
    else return presum[r-1] - presum[l - 1];
}

MAX_sum better(MAX_sum a,MAX_sum b) {
    if (a.data != b.data)return a.data > b.data ? a : b;
    else if (a.L != b.L)return a.L < b.L ? a : b;
    else return a.R < b.R ? a : b;
}

void segtree_init(int k, int l, int r) {//区间[l,r)
    if (r - l == 1) {
        max_prefix[k] = MAX_prefix(D[l], l);
        max_suffix[k] = MAX_suffix(D[l], l);
        max_sum[k] = MAX_sum(D[l], l, l);
    }
    else {
        int mid = (l + r) >> 1, chl = (k << 1) + 1, chr = (k << 1) + 2;
        segtree_init(chl, l, mid);
        segtree_init(chr, mid, r);
        
        if (max_prefix[chl].data >= sum(l,mid) + max_prefix[chr].data)
            max_prefix[k] = max_prefix[chl];
        else max_prefix[k] = MAX_prefix(sum(l,mid) + max_prefix[chr].data, max_prefix[chr].R);
        if (max_suffix[chr].data > max_suffix[chl].data + sum(mid,r))
            max_suffix[k] = max_suffix[chr];
        else max_suffix[k] = MAX_suffix(sum(mid,r) + max_suffix[chl].data, max_suffix[chl].L);
        max_sum[k] = better(max_sum[chl],max_sum[chr]);
        max_sum[k] = better(max_sum[k], MAX_sum(max_suffix[chl].data + max_prefix[chr].data, max_suffix[chl].L, max_prefix[chr].R));
    }
}

MAX_prefix seg_pre_query(int a, int b, int k, int l, int r) {
    if (a <= l&&b >= r) {
        return max_prefix[k];
    }
    else if (a >= r || b <= l) {//完全不相交
        return MAX_prefix(-MAX, INF);
    }
    else {
      int chl = (k << 1) + 1, chr = (k << 1) + 2, mid = (l + r) >> 1;
      MAX_prefix  p1=seg_pre_query(a, b, chl, l, mid);
      MAX_prefix  p2=seg_pre_query(a, b, chr, mid, r);
      return p1.data >= p2.data + sum(l, mid) ? p1 : MAX_prefix(p2.data + sum(l, mid), p2.R);
    }
}

MAX_suffix seg_suf_query(int a,int b,int k,int l,int r) {
    if (a <= l&&b >= r) {
        return max_suffix[k];
    }
    else if (a >= r || b <= l) {
        return MAX_suffix(-MAX,INF);
    }
    else {
        int chl = (k << 1) + 1, chr = (k << 1) + 2, mid = (l + r) >> 1;
        MAX_suffix  p1 = seg_suf_query(a, b, chl, l, mid);
        MAX_suffix  p2 = seg_suf_query(a, b, chr, mid, r);
        return p2.data > p1.data + sum(mid, r) ? p2 : MAX_suffix(p1.data + sum(mid, r), p1.L);
    }
}

MAX_sum  seg_query(int a, int b, int k, int l, int r) {
    if (a <= l&&b >= r) {
        return max_sum[k];
    }
    else if (a >= r || b <= l) {//完全不相交
        return MAX_sum(-MAX,INF,INF);
    }
    else {
        int mid = (l + r) >> 1, chl = (k << 1) + 1, chr = (k << 1) + 2;
        MAX_sum sum1 = seg_query(a, b, chl, l, mid);
        MAX_sum sum2 = seg_query(a, b, chr,mid, r);
        MAX_prefix pre = seg_pre_query(a, b, chr, mid, r);//mid一定在[a,b)区间当中
        MAX_suffix suf = seg_suf_query(a, b, chl, l, mid);//同理
        MAX_sum sum3 = MAX_sum(pre.data + suf.data, suf.L, pre.R);
        MAX_sum SUM = better(sum1, sum2);
        SUM = better(SUM,sum3);
        return SUM;
    }
}

int main() {
    int Case = 0;
    while (scanf("%d%d",&n,&m)!=EOF) {
        for (int i = 0; i < n; i++) {
            scanf("%d", &D[i]);
            if (!i)presum[i] = D[i];
            else presum[i] = presum[i - 1] + D[i];
        }
        segtree_init(0,0,n);
        printf("Case %d:\n",++Case);
        for (int cs = 1; cs <= m; cs++) {
            int a, b; scanf("%d%d", &a, &b); a--;
            MAX_sum ans=seg_query(a,b,0,0,n);
            printf("%d %d\n",ans.L+1,ans.R+1);
        }
    }
    return 0;
}

/*
8 1
3 -4 1 3 -2 5 1 3
2 6
*/