Merge branch 'master' of git@github.com:brianchenming/algorithms

1009/edge.cpp

@@ -0,0 +1,160 @@
+/*
+ * =====================================================================================
+ *
+ *       Filename:  edge.cpp
+ *
+ *    Description:  POJ 1009
+ *
+ *        Version:  1.0
+ *        Created:  09/18/2010 03:54:14 PM
+ *       Revision:  none
+ *       Compiler:  gcc
+ *
+ *         Author:  Ming Chen (chenming), chenming@sohu-rd.com
+ *        Company:  imeresearch@sogou
+ *
+ * =====================================================================================
+ */
+
+#include	<iostream>
+#include	<algorithm>
+#include	<stdlib.h>
+
+using namespace std;
+
+const int MAX_RLE = 1000;
+const int MAX_VAL = 256;
+const int MAX_OFFSET = 1000000000;
+
+int rles[MAX_RLE][2], nrle = 0;
+int height, width, total;
+int checkpoints[9*MAX_RLE], numpoint = 0;
+int neighbors[9];
+
+/* 
+ * ===  FUNCTION  ======================================================================
+ *         Name:  find_neighbors
+ *  Description:  
+ * =====================================================================================
+ */
+    void
+find_neighbors ( int pos )
+{
+    static int offsets[9][2] = {
+        {-1, -1}, {0, -1}, {1, -1},
+        {-1, 0}, {0, 0}, {1, 0},
+        {-1, 1}, {0, 1}, {1, 1}
+    };
+    int yi = pos / width;
+    int xi = pos % width;
+    for (int i = 0; i < 9; ++i) {
+        int nxi = xi + offsets[i][0];
+        int nyi = yi + offsets[i][1];
+        if ( nxi < 0 || nxi >= width || nyi < 0 || nyi >= height ) {
+            neighbors[i] = -1;
+        } else {
+            neighbors[i] = nxi + nyi*width;
+        }
+    }
+}		/* -----  end of function find_neighbors  ----- */
+
+/* 
+ * ===  FUNCTION  ======================================================================
+ *         Name:  add_checkpoints
+ *  Description:  
+ * =====================================================================================
+ */
+    void
+add_checkpoints ( int pos )
+{
+    find_neighbors(pos);
+    for ( int i = 0; i < 9; ++i ) { 
+        if ( neighbors[i] == -1 ) continue;
+        checkpoints[numpoint++] = neighbors[i];
+    }
+}		/* -----  end of function add_checkpoints  ----- */
+
+/* 
+ * ===  FUNCTION  ======================================================================
+ *         Name:  get_edge
+ *  Description:  
+ * =====================================================================================
+ */
+    int
+get_edge ( int pos, int* pfrom_rle )
+{
+    int values[9], irle = *pfrom_rle;
+    int new_from_rle = -1;                      // find a new start from pfrom_rle
+    find_neighbors(pos);                        
+    for ( int i = 0; i < 9; ++i ) {
+        if ( neighbors[i] == -1 ) {
+            values[i] = MAX_VAL;
+            continue;
+        }
+
+        while ( rles[irle][1] <= neighbors[i] ) ++irle; // locate rle containing current neighbor
+        values[i] = rles[irle][0];
+
+        if ( new_from_rle == -1 ) {                     // set new from_rle if not set
+            new_from_rle = *pfrom_rle;
+            while ( neighbors[i] > (rles[new_from_rle][1] + width + 1) ) 
+                ++new_from_rle; 
+        }
+    }
+    *pfrom_rle = new_from_rle;
+
+    int edge = 0;
+    for ( int i = 0; i < 9; ++i ) {
+        if ( values[i] == MAX_VAL ) continue;
+        edge = max(edge, abs(values[i] - values[4]));
+    }
+
+    return edge;
+}		/* -----  end of function get_edge  ----- */
+
+/* 
+ * ===  FUNCTION  ======================================================================
+ *         Name:  main
+ *  Description:  
+ * =====================================================================================
+ */
+    int
+main ( int argc, char *argv[] )
+{ 
+    while ( cin >> width && width != 0 ) {
+        total = 0;
+        int val, len;
+        for ( nrle = 0; cin >> val >> len && (len != 0 || val != 0); ++nrle ) {
+            total += len;
+            rles[nrle][0] = val;
+            rles[nrle][1] = total;
+        }
+        height = total / width;
+        // add check points
+        numpoint = 0;
+        add_checkpoints(0);
+        for ( int i = 0; i < nrle; ++i ) 
+            add_checkpoints(rles[i][1]);
+        sort(checkpoints, checkpoints+numpoint);
+        numpoint = unique(checkpoints, checkpoints+numpoint) - checkpoints;
+
+        cout << width << "\n";
+        int edge_val, begin_pos = 0, from_rle = 0;
+        edge_val = get_edge(begin_pos, &from_rle);
+        for ( int i = 0; i < numpoint; ++i ) {
+            int edge = get_edge(checkpoints[i], &from_rle);
+            if ( edge != edge_val ) {
+                cout << edge_val << " " << (checkpoints[i] - begin_pos) << "\n"; 
+                edge_val = edge;
+                begin_pos = checkpoints[i];
+            }
+        }
+        if ( begin_pos < total ) {
+            cout << edge_val << " " << (total - begin_pos) << "\n";
+        }
+        cout << "0 0\n";
+    }
+    cout << "0\n";
+
+    return EXIT_SUCCESS;
+}				/* ----------  end of function main  ---------- */