UVALive - 3938 "Ray, Pass me the dishes!"

白书上讲的已经很明白了....

#include <cstdio>#include <cstdlib>#include <cstring>#include <iostream>#include <algorithm>#include <set>#include <map>#include <utility>#include <algorithm>using namespace std;const int MAXN = 500010;typedef long long ll;ll  max_sum[MAXN<<2];int max_prefix[MAXN<<2], max_suffix[MAXN<<2], range_x[MAXN<<2], range_y[MAXN<<2];ll  prefix[MAXN], suffix[MAXN], val[MAXN];int n, q;void push_up(int rt, int l, int r){    int x1 = max_prefix[rt<<1], y1 = max_suffix[rt<<1],\        x2 = max_prefix[rt<<1|1], y2 = max_suffix[rt<<1|1];    if(prefix[x1] - prefix[l-1] >= prefix[x2] - prefix[l-1])        max_prefix[rt] = x1;    else        max_prefix[rt] = x2;    if(suffix[y2] - suffix[r+1] > suffix[y1] - suffix[r+1])        max_suffix[rt] = y2;    else        max_suffix[rt] = y1;    if(max_sum[rt<<1] >= max_sum[rt<<1|1])    {        max_sum[rt] = max_sum[rt<<1];        range_x[rt] = range_x[rt<<1];        range_y[rt] = range_y[rt<<1];    }    else    {        max_sum[rt] = max_sum[rt<<1|1];        range_x[rt] = range_x[rt<<1|1];        range_y[rt] = range_y[rt<<1|1];    }    if((prefix[x2] - prefix[y1-1] > max_sum[rt]))    {        range_x[rt] = y1;        range_y[rt] = x2;        max_sum[rt] = prefix[x2] - prefix[y1-1];    }    else if((prefix[x2]-prefix[y1-1]) == max_sum[rt])    {        if(y1 == range_x[rt] && x2 < range_y[rt])        {            range_x[rt] = y1;            range_y[rt] = x2;        }        else if(y1 < range_x[rt])        {            range_x[rt] = y1;            range_y[rt] = x2;        }    }    return ;}void bulid(int l, int r, int rt){    if(l == r)    {        max_sum[rt] = val[l];        max_prefix[rt] = l;        max_suffix[rt] = l;        range_x[rt] = l;        range_y[rt] = l;        return ;    }    int m = (l + r)>>1;    bulid(l, m, rt<<1);    bulid(m + 1, r, rt<<1|1);    push_up(rt, l, r);    return ;}pair< pair<int,int>,pair<int,int> > query(int L, int R, int l, int r, int rt){    if(L == l && R == r)    {        return make_pair(make_pair(max_prefix[rt], max_suffix[rt]),make_pair(range_x[rt], range_y[rt]));    }    int m = (l + r)>>1;    if(R <= m)    {        return query(L, R, l, m, rt<<1);    }    else if(L > m)    {        return query(L, R, m + 1, r, rt<<1|1);    }    else    {        pair< pair<int,int>,pair<int,int> > tmp1 = query(L, m, l, m, rt<<1);        pair< pair<int,int>,pair<int,int> > tmp2 = query(m + 1, R, m + 1, r, rt<<1|1);        pair< pair<int,int>,pair<int,int> > tmp3;        if(prefix[tmp1.first.first] - prefix[L-1] >= prefix[tmp2.first.first] - prefix[L-1])        {            tmp3.first.first = tmp1.first.first;        }        else        {            tmp3.first.first = tmp2.first.first;        }        if(suffix[tmp1.first.second] - suffix[R+1] >= suffix[tmp2.first.second] - suffix[R+1])        {            tmp3.first.second = tmp1.first.second;        }        else        {            tmp3.first.second = tmp2.first.second;        }        ll tmp;        if(prefix[tmp1.second.second] - prefix[tmp1.second.first-1] >= prefix[tmp2.second.second] - prefix[tmp2.second.first-1])        {            tmp = prefix[tmp1.second.second] - prefix[tmp1.second.first-1];            tmp3.second.first = tmp1.second.first;            tmp3.second.second = tmp1.second.second;        }        else        {            tmp = prefix[tmp2.second.second] - prefix[tmp2.second.first-1];            tmp3.second.first = tmp2.second.first;            tmp3.second.second = tmp2.second.second;        }        if(prefix[tmp2.first.first] - prefix[tmp1.first.second-1] > tmp)        {            tmp3.second.first = tmp1.first.second;            tmp3.second.second = tmp2.first.first;        }        else if(prefix[tmp2.first.first] - prefix[tmp1.first.second-1] == tmp)        {            if(tmp1.first.second < tmp3.second.first || (tmp1.first.second == tmp3.second.first && tmp2.first.first < tmp3.second.second))            {                tmp3.second.first = tmp1.first.second;                tmp3.second.second = tmp2.first.first;            }        }        return tmp3;    }}int main(){    //freopen("aa.in", "r", stdin);    int kcase = 0, x, y;    pair< pair<int,int>,pair<int,int> > ret;    while(scanf("%d %d", &n, &q) != EOF)    {        kcase++;        memset(prefix, 0, sizeof(prefix));        memset(suffix, 0, sizeof(suffix));        for(int i = 1; i <= n; ++i)        {            cin >> val[i];            prefix[i] = prefix[i-1] + val[i];        }        for(int i = n; i >= 1; --i)        {            suffix[i] = suffix[i+1] + val[i];        }        bulid(1, n, 1);        printf("Case %d:\n", kcase);        for(int i = 1; i <= q; ++i)        {            scanf("%d %d", &x, &y);            ret = query(x, y, 1, n, 1);            printf("%d %d\n", ret.second.first, ret.second.second);        }    }    return 0;}