UVA 12299 RMQ with Shifts

UVA_12299

    这个是湖南省赛的题目，要是早点能学到YTQ后来给我PPT的话，当时也许就过掉了。

    这个题目比一般的RMQ多了一个shift操作，用堆存储线段树然后直接自底向上更新一下即可。

#include<stdio.h>
#include<string.h>
#include<ctype.h>
#define MAXD 100010
#define INF 1000000000
int N, M, Q, tree[4 * MAXD];
char b[50];
int a[50], d[50], n;
int Min(int &x, int &y)
{
    return x < y ? x : y;
}
void init()
{
    int i, j;
    for(M = 1; M < N + 2; M <<= 1);
    for(i = M; i < 2 * M; i ++)
        tree[i] = INF;
    for(i = 0, j = M + 1; i < N; i ++, j ++)
        scanf("%d", &tree[j]);
    for(i = M - 1; i; i --)
        tree[i] = Min(tree[2 * i], tree[2 * i + 1]);
}
void change(int cur, int target)
{
    int i, j;
    cur += M;
    tree[cur] = target;
    for(; cur ^ 1; cur >>= 1)
        tree[cur >> 1] = Min(tree[cur], tree[cur ^ 1]);
}
void solve()
{
    int i, j, k, res, s, t;
    scanf("%s", b);
    if(b[0] == 's')
    {
        n = 0;
        for(i = 0; b[i]; i ++)
        {
            if(isdigit(b[i]))
                sscanf(&b[i], "%d", &a[n ++]);
            while(isdigit(b[i]))
                i ++;
        }
        for(i = 0; i < n; i ++)
        {
            if(i == n - 1)
                d[i] = tree[M + a[0]];
            else
                d[i] = tree[M + a[i + 1]];
        }
        for(i = 0; i < n; i ++)
            change(a[i], d[i]);
    }
    else
    {
        sscanf(&b[6], "%d", &s);
        sscanf(strchr(b, ',') + 1, "%d", &t);
        res = INF;
        s = s - 1 + M;
        t = t + 1 + M;
        for(; s ^ t ^ 1; s >>= 1, t >>= 1)
        {
            if(~s & 1)
            {
                res = tree[s ^ 1] < res ? tree[s ^ 1] : res;
            }
            if(t & 1)
            {
                res = tree[t ^ 1] < res ? tree[t ^ 1] : res;
            }
        }
        printf("%d\n", res);
    }
}
int main()
{
    while(scanf("%d%d", &N, &Q) == 2)
    {
        init();
        for(int i = 0; i < Q; i ++)
            solve();
    }
    return 0;
}