Lecture 2

README.md

@@ -12,3 +12,7 @@
 
 ### SoSe24/lec01_alg
 - Beispiele aus der ersten Vorlesung
+
+### SoSe24/lec02_alg
+- Beispiele aus der zweiten Vorlesung 
+- erstes Praktikum

SoSe24/lec02_maxfolge/cubic.py

@@ -0,0 +1,26 @@
+from SoSe24.algodat.foundation import AlgoDatArray, AlgoDatValue, read_int_sequence, MinusInf
+from time import perf_counter as pfc
+
+def maxfolge1(z: AlgoDatArray) -> (int, int, int):
+    maximum = AlgoDatValue(MinusInf())
+    current_sum = AlgoDatValue(0)
+    left = AlgoDatValue(0)
+    right = AlgoDatValue(0)
+    for i in range(z.size):
+        for j in range(i, z.size):
+            current_sum.value = 0
+            for k in range(i, j + 1):
+                current_sum += z[k]
+            if current_sum > maximum:
+                maximum.value = current_sum.value
+                left.value = i
+                right.value = j
+    return maximum.value, left, right
+
+
+if __name__ == "__main__":
+    z = read_int_sequence("../../seq0.txt")
+    start = pfc()
+    print(maxfolge1(z))
+    print(f"Dauer: {pfc() - start:.4f}s")
+    AlgoDatValue.summary()

SoSe24/lec02_maxfolge/divide_et_impera.py

@@ -0,0 +1,44 @@
+from SoSe24.algodat.foundation import AlgoDatArray, AlgoDatValue, read_int_sequence, MinusInf
+from time import perf_counter as pfc
+def in_between(z: AlgoDatArray, l: int, m: int, r: int) -> (AlgoDatValue, int, int):
+    left_max = AlgoDatValue(MinusInf())
+    left = AlgoDatValue(0)
+    current_sum = AlgoDatValue(0)
+    for i in range(m, l - 1, -1):
+        current_sum += z[i]
+        if current_sum > left_max:
+            left_max.value = current_sum.value
+            left.value = i
+    right_max = AlgoDatValue(MinusInf())
+    right = AlgoDatValue(0)
+    current_sum.value = 0
+    for i in range(m + 1, r + 1):
+        current_sum += z[i]
+        if current_sum > right_max:
+            right_max.value = current_sum.value
+            right.value = i
+    return left_max + right_max, left, right
+
+def maxfolge_part(z: AlgoDatArray, l:int, r:int) -> (int, int, int):
+    if l == r:
+        return z[l].value, l, r
+    m = (l + r) // 2
+    left_sum, left_left, left_right = maxfolge_part(z, l, m)
+    right_sum, right_left, right_right = maxfolge_part(z, m + 1, r)
+    cross_sum, cross_left, cross_right = in_between(z, l, m, r)
+    if left_sum >= right_sum and left_sum >= cross_sum:
+        return left_sum, left_left, left_right
+    elif right_sum >= left_sum and right_sum >= cross_sum:
+        return right_sum, right_left, right_right
+    else:
+        return cross_sum, cross_left, cross_right
+
+def maxfolge3(z: AlgoDatArray) -> (int, int, int):
+    return maxfolge_part(z, 0, z.size - 1)
+
+if __name__ == "__main__":
+    z = read_int_sequence("../../seq3.txt")
+    start = pfc()
+    print(maxfolge3(z))
+    print(f"Dauer: {pfc() - start:.4f}s")
+    AlgoDatValue.summary()

SoSe24/lec02_maxfolge/linear.py

@@ -0,0 +1,27 @@
+from SoSe24.algodat.foundation import AlgoDatArray, AlgoDatValue, read_int_sequence, MinusInf
+from time import perf_counter as pfc
+
+def maxfolge4(z: AlgoDatArray) -> (int, int, int):
+    maximum = AlgoDatValue(MinusInf())
+    current_sum = AlgoDatValue(0)
+    current_left = AlgoDatValue(0)
+    left = AlgoDatValue(0)
+    right = AlgoDatValue(0)
+    for i in range(z.size):
+        current_sum += z[i]
+        if current_sum > maximum:
+            maximum.value = current_sum.value
+            left.value = current_left.value
+            right.value = i
+        if current_sum < 0:
+            current_sum.value = 0
+            current_left.value = i + 1
+    return maximum.value, left, right
+
+
+if __name__ == "__main__":
+    z = read_int_sequence("../../seq3.txt")
+    start = pfc()
+    print(maxfolge4(z))
+    print(f"Dauer: {pfc() - start:.4f}s")
+    AlgoDatValue.summary()

SoSe24/lec02_maxfolge/quad.py

@@ -0,0 +1,25 @@
+from SoSe24.algodat.foundation import AlgoDatArray, AlgoDatValue, read_int_sequence, MinusInf
+from time import perf_counter as pfc
+
+def maxfolge2(z: AlgoDatArray) -> (int, int, int):
+    maximum = AlgoDatValue(MinusInf())
+    current_sum = AlgoDatValue(0)
+    left = AlgoDatValue(0)
+    right = AlgoDatValue(0)
+    for i in range(z.size):
+        current_sum.value = 0
+        for j in range(i, z.size):
+            current_sum += z[j]
+            if current_sum > maximum:
+                maximum.value = current_sum.value
+                left.value = i
+                right.value = j
+    return maximum.value, left, right
+
+
+if __name__ == "__main__":
+    z = read_int_sequence("../../seq0.txt")
+    start = pfc()
+    print(maxfolge2(z))
+    print(f"Dauer: {pfc() - start:.4f}s")
+    AlgoDatValue.summary()