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");





    }

}