hdu_1025

LIS，只求长度，不求串的具体内容

// hdu 1025
// dp LIS binary_search
// Feb.16 2015

#include <cstdio>

#define MAXN 500000

int dp[MAXN + 10], n, road[MAXN + 10], case_num = 0, len;
// dp[i] 代表长度为i的LIS的末尾数字
// int locate_time = 0;

int binary_search(int num)
{
    // 找到一个x的值，使得num刚好不小于dp[x]
    // 使得 num 可以添加到这个dp[x]对应的LIS后面
    int l = 1, r = len;
    while(l <= r){
        int mid = (l+r)>>1;
        if(num == dp[mid]){
            // printf("The %d time...%d equal to dp[%d]\n", ++locate_time, num, mid);
            return mid;
        }
        if(dp[mid] < num)
            l = mid + 1;
        if(dp[mid] > num)
            r = mid - 1;
    }
    // printf("The %d time...locate the pos %d\n", ++locate_time, l);
    return l;
}

int main(int argc, char const *argv[])
{
    freopen("in", "r", stdin);
    while(~scanf("%d", &n)){
        for(int i = 1, poor, rich; i <= n; ++i){
            scanf("%d%d", &poor, &rich);
            road[poor] = rich;
        }
        dp[1] = road[1];
        len = 1;
        // 初始状态，LIS长度为1，且LIS末尾数字，为road[1]
        for(int i = 1; i <= n; ++i){
            int temp = binary_search(road[i]);
            // 当前road[i]的值最多能够放到长度为temp的LIS后面
            // 然后更新这个长度为temp的LIS的值
            dp[temp] = road[i];
            // 如果长度为temp的LIS是当前最长LIS，则更新len值
            if(temp > len)
                ++len;
        }
        printf("Case %d:\nMy king, at most %d road", ++case_num, len);
        if(len > 1)
            printf("s");
        printf(" can be built.\n\n");

    }
}